Part 1

Chapter 1: The Hunting Ground

The book starts out with a giant Traction City, London, rolling across the Great Hunting Ground, where Europe and Asia were formerly. It is chasing a small Traction Town named Salthook for resources.

15-year-old Apprentice Historian Thomas "Tom" Natsworthy is dusting the relics in the London Museum when London chases Salthook. He puts one of his hands to the metal wall of the museum when Historian Chudleigh Pomeroy walks in. He demands why Tom isn't working and Tom says "It's a chase, sir". Tom asks if he can go watch and Pomeroy says that all the relics have dust on them, and Tom says he just dusted them (I think London moving has put more dust on relics) and says that it isn't fair. Pomeroy snaps that "Life isn't fair" and threatens him, saying that if he disobeys, he will go to The Gut to look for relics. Tom cleans some of the relics as Pomeroy walks out and when he notices Chudleigh isn't watching him, he hides his supplies and goes to "Tottenham Court Road" on Tier Two (where Tom works) to watch the chase. As Tom watches, Herbert Melliphant, a First Class Apprentice, comes up to Tom and begins harassing him. Following Herbert is 16-year-old Clytie Potts, a new Historian, whom Tom is attracted to. In a few minutes the chase is over and Cytie thinks about inviting Tom to a party to celebrate the catch. Herberts says no since Tom is a Third Class Apprentice and his parents Rebecca Natsworthy and David Natsworthy were killed in The Big Tilt for him to not have a good apprenticeship. Enraged, Tom punches Herbert and Herbert beats Tom up before Pomeroy finds Tom fighting Hebert and saves Tom's life and sends him down to The Gut.

Chapter 2: Valentine

Tom is sent to The Gut to search for relics in the items recovered from Salthook. He thinks that if Dr. Arkengarth or Dr. Weymouth supervise him, he's in trouble. But, if it's Potty Pewtertide or Ms. Plym, he's good. As Tom walks through The Gut, he sees Thaddeus Valentine's men, Pewsey and Gench helping the Engineers. Then, when he walks further into The Gut, Tom finds Thaddeus Valentine, Katherine Valentine, and Dog. Katherine Valentine is Thaddeus Valentine's daughter and Hester Shaw's half-sister, while Dog is Katherine's pet wolf.

Tom, Thaddeus, Katherine, and Dog walk through The Gut to Salthook's relic pile and Tom finds a CD in it. Thaddeus says that it could be important in the future and he takes the band to Incomer's Station, "where the former inhabitants were queuing to give their names to the Clerk of Admissions and be taken up to new homes in the hostels and workhouses of London." As Valentine speaks to some men there, an unknown Hester Shaw takes a knife out of her coat and tries to stab Thaddeus in the heart.

Chapter 3: The Waste Chute

Tom suddenly runs over to an unknown Hester and grabs her wrist to prevent Thaddeus from being assassinated. The teen flees the scene and Katherine orders "Stop her!" Tom chases her and yells "Stop her!" as he's running and an unknown Bevis Pod joins the chase. When Tom corners an unnamed Hester at the railing of the waste chute (the police shoot an arrow at Hester's leg in the process), Tom sees "She was no older than Tom, and she was hideous. A terrible scar ran down her face from forehead to jaw, making it look like a portrait that had been furiously crossed out. Her mouth was wretched sideways in a permanent sneer, her nose was a single stump, and her single eye stared at him out of the wreckage, as gray and chill as a winter sea." Unnamed Hester hisses at Tom why he prevented Thaddeus' murder and Tom says that "He's a good man, a kind, brave, wonderful-" before being cut off and the girl says "Ask him what he did to Hester Shaw!" before jumping through the waste chute. Thaddeus, the London Police Fore, and an unknown Bevis Pod catches up with Tom and Thaddeus demands to know what Hester looked like. Tom wonders why Thaddeus knows about Hester's appearance before Thaddeus shoves Tom down the waste chute into Out-Country, or the outside world.

Chapter 4: The Out-Country

Tom wakes up outside London in Out-Country, and realizes he's on mud. As he stands up, he sees he's shirtless and that Hester is using his shirt as a bandage for her arrow wound. Then, he snatches up his tunic (the underpart of his shirt) and throws his ripped shirt away. Hester growls that he should've let her kill him as she tries to walk and Tom catches up with her. Tom feels guilty for stopping Hester and begins to cry. Hester notices it and says she never cries, even when her parents were murdered. Tom accuses her of lying and Hester retorts, saying "How come you're here, then?" Tom realizes that Thaddeus pushed him out of London and he decides to team up with Hester to get back to London.

Chapter 5: The Lord Mayor

In Thaddeus' estate in London, Katherine thinks about Tom, about how he was killed by following Hester. Feeling curious, Kate gets into her clothes she wore earlier (they "still smelling of furnaces") and passes a "statue of Clio, goddess of History" and into the dining room. Thaddeus sees his daughter and greets her. Kate tells Thaddeus about Tom and the Head Historian tells her that Lord Mayor Magnus Crome is upset and that his and Thaddeus will have a meeting. Kate notices Hester's backpack on the ground and find dried meat, a first aid kit, matches, a water bottle, "some string", and a form for when Hester was in Strole (with a picture of Hester attached to it). Kate tells her father about the picture and Thaddeus, in haste, burns the form and picture with a lighter. He puts in an ashtray on his ornate desk. Just then, Pewsey enters the dining room and says that Magnus Crome has arrived. Thaddeus is shocked and runs to the door of his estate. Crome arrives with some Beefeaters at his side and also with Gench, Pewsey's friend. Katherine is kept out of the meeting, alongside Dog, and Crome and Thaddeus talk about killing Hester and their plan to unleash MEDUSA. Katherine runs back to her room and wonders about how Hester could be Thaddeus' "ghost from his past" and what MEDUSA is.

Chapter 6: Speedwell

As Tom and Hester walk in Out-Country, Tom becomes homesick. As Tom thinks about London, Hester accidentally falls and she snaps at him. Tom thinks the thing about London he misses the most is "the food. It had never been much, the stuff they served in the Guild canteen, but it was better than nothing, and nothing was what he had now." Much more in the day, Hester would stop and catch something, but never give anything to Tom. At night, when both rest for the night, Hester tells Tom her backstory. 

Hester Shaw was born on Oak Island in the town of Dunroamin' to Pandora Rae and Davis Shaw. David was a farmer and Pandora was a Historian, albeit "a lot cleverer than you [Tom Natsworthy], of course." When Hester was 7, Thaddeus Valentine stormed into the Shaw household and demanded that Pandora give him the plans for MEDUSA. In rage, Pandora screeches "Damn you, Thaddeus, I found it, it's mine!" Thaddeus then murders Pandora and David with his sword and when he notices a 7-year-old Hester watching, he slashes her face with the sword and she falls backward, making Thaddeus believe he killed Hester. Hester then escapes by a fishing boat at sea as Thaddeus' cronies chase her and try to kill her.

Tom asks Hester about MEDUSA and she says she doesn't know what it is. She then goes to sleep and Tom decides to actually team up with her to find Thaddeus.

The next day, London is out of Tom and Hester's reach and Hester's wound is infected. Tom hates himself for ripping Hester's backpack off of her during the chase. At noon, they find what look like people scavenging a dead Traction Town and Tom and Hester run to it. Actually, it is Speedwell, a Traction Town run by Mayer Orme Wreyland. Once Hester and Tom meet the mayor, Tom asks if they can give food and shelter to both of them and medical attention to Hester's wound. Orme says they can give them food and shelter, but no medical attention and tells them they need to pay for their food and shelter. Tom decides to give his CD to Orme, even though he going to make a present out of it for Katherine Valentine.

The shelter is okay, but the food is awful. The food that Tom and Hester eat are some kind of blue algae, made underneath Speedwell. Tom asks Orme about Speedwell, and the mayor says the Town is fast and "It's no run, running a traction town". Tom asks for a hitch to London, but Orme says London recycles from now on. Suddenly, Hester is out cold (from the algae) and Tom begins to feel knocked out by the algae. Orme says that Speedwell is going to a Trading Cluster and Tom almost finds out Speedwell is a trap before being knocked out and dreaming of Katherine.

Chapter 7: High London

At London, on Top Tier where three important building stand, Lord Mayor Magnus Crome enters Engineerium to talk to Dr. Evadne Twix, who is obsessed with robotic resurrected Stalkers. A monorail car takes him to where Evadne works and an Apprentice Engineer actually takes Magnus to her. Evadne greets Magnus and Magnus demands to see Shrike (Grike in the North American version), a Stalker. As both people to where Shrike is, Evadne says Shrike loves Hester and wants him "dismantled". Magnus grunts he has a job for him and when they find him, Magnus greets Shrike and says Hester is dead. A startled Shrike is horrified and then Magnus promises that if Shrike kills Hester and Thomas, then Shrike will be rich.

Katherine is in her bedroom eavesdropping on "Mrs. Mallow, the housekeeper" and an unknown servant about Thaddeus and Magnus' plan. Later that day, Katherine asks her father about what he need to find (since finding is a Navigator's job). Thaddeus says he will be away for a month and grumbles about Pewsey and Gench screwing up his airship, the 13th Floor Elevator.

In the Navigator airship hangar, the 13th Floor Elevator is being packed. Dog is sniffing the items. Katherine begs her father if she can come, and he says no because he thinks it could be dangerous (not because Katherine is a girl, which was her original thought). Katherine then pesters her father about where he's going and Thaddeus says Shan Guo, the capital of the Anti-Tractionist League. Katherines wonders if Shan Guo has something to do with Hester and Thaddeus says no as airship from the Guild of Engineers departs.

Chapter 8: The Trading Center

Tom dreams of Katherine walking with him in London Museum without anyone telling him to do any chores. In the dream, the song of a blue whale is heard, but when Tom wakes up in wooden cage in Speedwell with Hester, he realizes the blue whale song is just gently creaking wood. Tom asks Hester where they are and she doesn't know. Tom hisses that we will never get home and then Orme looks through a wooden cat flap at the bottom of the door in front of Tom and Hester's prison and checks up on them before giving them water and blue algae. Tom and Hester drink the water and then, they are at the Trading Cluster. Tom and Hester plan to escape and when Tom finds a loose wooden plank, he breaks it open and hisses at Hester to help him break the rest of the wood. Hester does and the teens escape.

Shrike is with some airships when they spot Tom's rag-like shirt. Shrike determines Hester was there and beings looking for her.

Chapter 9: The Jenny Haniver

As Tom and Hester run into the Trading Cluster, one of Orme's nephews notifies Orme about an escaping Tom and Hester. Hester is in pain as both teens escape. Tom heads straight for the airship boarding area, which is "an airmen's café", "an ancient, rusting airship gondola that had been bolted to the deck. A few metal tables stood in front, beneath a stripy awning. Hurricane lamps were burning, and there was an old aviator slumped snoring in a chair." The only other  person there is an unnamed Anna Fang. The man there notices Tom and Hester and Tom asks him for a hitch to London. The man says "Only ships with a license from the London Merchants' Guild can dock there. We've got nothin' like that here. Stayns ain't that sort of town." Unnamed Anna Fang suggests she can hitch Tom and Hester to London and Tom gives her two dollar bills with "the face of Quirke on the front and Magnus Crome gazing sternly from the back." They are worth "Twenty Quirkes." But, unnamed Anna Fang says that Quirkes can only be used in London only and she needs gold or "Old Tech" (technology in today's modern present times since this is a steampunk sci-fi book). Suddenly, Orme and his cronies appear and demand that Tom and Hester be returned. Tom and Hester run to the airship quays and are suddenly trapped when Orme catches up to them. Orme almost attacks them, but Hester strikes first with a metal lever from an airship and almost beats Orme to death, if Tom had not interfered. Then, unnamed Anna Fangs leads Tom and Hester to her ship, the Jenny Haniver and introduces herself. When Tom sees the Jenny, he calls it crap. Anna laughs and Tom, Anna, and Hester get on. As Anna turns on her airship's power to leave, a radio voice tells her to surrender Tom and Hester. Anna ignores it and flies off into the night to Airhaven.

Chapter 10: The 13th Floor Elevator

The same night Tom and Hester meet Anna Fang, Thaddeus Valentine leaves for his mission to Shan Guo in his airship, the 13th Floor Elevator. Katherine waves goodbye and the rest of London celebrates his departure. When Thaddeus leaves, Katherine decides to dive into the mystery of Hester Shaw.

Chapter 11: Airhaven

The next morning, Tom drinks hot chocolate with Anna and thinks that adventuring is awesome. Anna has led Hester into the medical ward and treated her wound during the night. Anna and Tom talk about Thaddeus and Hester as the day goes on. They also talk about Thaddeus and Magnus' plans for London. When Tom says that London will find more prey in the Central Hunting Grounds, Anna shows Tom the Central Hunting Grounds and both figure that can't be what London's out for. Anna then decides to take Tom and Hester to Airhaven to get both of them to London.

Tom mentions that Airhaven had once floated above London and couldn't sight-see that day, since he was a Third Class Apprentice. He finds Hester in the medical ward and sees Airhaven through a window. He points out "The Floating Exchange, and that church is St. Michael's-in-the-Sky - there's a picture of it in the London Museum!" Hester and Anna are annoyed with him. As the Jenny Haniver is docked, Anna pays someone to guard her airship and Tom sees warnings about fire on Airhaven. As soon as they get inside, Tom thinks he will remember Airhaven for the rest of his life. Anna promises to take Tom and Hester to an inn "along the curve of High Street" called "the Gasbag and Gondola." It is "a building with a sign in the shape of an airship." As they enter, Tom swears he saw a ship with the sigil of the Guild of Engineers, "a red wheel", dock on Airhaven.

Chapter 12: The Gasbag and Gondola

Anna, Tom, and Hester walk into the inn (which includes shrines to "The god of aviators" and "the Lady of the High Heavens") and have lunch with Captain Khora of the Mokele Mbembe, Nils Lindstrom of the Garden Aeroplane, and Yasmina Rashid of the Zainab. Hester and Tom are horrible at eating with chopsticks. As Khora talks to Tom and Anna tries to get him to try more food, "London airship GE47" docks and a Stalker enters the restaurant, ready to kill Tom and Hester. Hester knows that the Stalker is Shrike and tries to talk to him. The diplomatic talk fails and Hester and Tom are forced to flee, leaving Anna, Khora, Nils, and Yasmina behind. Tom and Hester steal a hot air balloon and float into the night.

Chapter 13: The Resurrected Men

As Hester and Tom float in the hot air balloon they stole, Hester tells Tom of how she met Shrike.

The day after Pandora Rae and David Shaw were murdered by Thaddeus Valentine for the MEDUSA plans, Shrike finds Hester. He takes her to a Traction Town called Strole and Shrike has a collection of Old Tech where he lives. When Hester tells him she has to go to London, he simply says "You must not go".

Tom feels bad for Hester and both teens talk about Airhaven and star charts before the sudden arrival of Shrike's ship forces Tom and Hester to go on foot in Out-Country. As soon as Tom and Hester jump out of hot air balloon, the force themselves to walk to safety.

Chapter 14: The Guildhall

Katherine is going to meet with Magnus Crome. She gets to meeting early and Magnus reports everything he got from a message. Katherine gets a little too cocky and asks about MEDUSA. Magnus ushers her away immediately. 

Katherine goes to "the Temple of Clio on the edge of Circle Park." She prays to the idol what she should do and also prays for Thaddeus Valentine and Tom Natsworthy. Then she goes home and plans to find the Apprentice Engineer who saw the incident in part 1, chapter 3 happen.

Chapter 15: The Rustwater Marshes

Tom and Hester walk through a marsh throughout the next day. Tom thinks they fooled Shrike, but Hester says he'll catch up with them immediately.

Tom and Hester keep walking until night and they talk about London and Tom's family before they see an airship above them suspiciously.

Shrike realizes he was fooled when the hot air balloon was shot down and Tom and Hester's corpses were not in it. He decides to track he drown and kill both teens before the can escape again.

Hester realizes the airship is Shrike's and Tom and Hester try to flee. Shrike suddenly come down from the ship and says Hester led him to London and that he will kill both teens. Shrike tells Hester about what happened while waiting for her and tries to murder them, but a huge Traction Town runs over Shrike and Tom and Hester get onto it.

Tom and Hester see that they've hitched onto Tunbridge Wheels, a pirate suburb.

As Tunbridge Wheels wheels on into the night, Shrike gets up out of the mud (the suburb ran over him) and instinctively begins hunting for Hester and Tom.

Chapter 16: The Turd Tanks

Katherine makes her way down into The Gut via an "elevator at Tartarus Row." As Katherine walks through the place, Engineers who don't know her greet her. She passes a statue of "Sooty Pete, the hunchbacked god of engine rooms and smokestacks" before finding out the name of the Apprentice who saw the Waste Chute incident: "Apprentice Engineer Pod."

Katherine makes her way to Deep Gut Prison and "Gut Supervisor Nimmo" assists her to Apprentice Pod, who is in "Section Sixty... on the underdecks." On their way to Section Sixty, Katherine notices human feces dropping down into a metal pool and people in aprons and rakes in hand search through it. Nimmo tells it the feces is used for fuel and that the Engineers are trying to turn it into a snack. Katherine gags at the thought and then, Nimmo and Katherine arrive at Section Sixty, where the pooled feces is. The workers are criminals and a girl hisses at Bevis, saying he's "wasting water again". The girl tells Nimmo and Katherine that the prisoner needs to work harder, but Bevis says the prisoner is sick. Katherine tells Nimmo the prisoner needs medical attention but Nimmo says that The Gut has no such thing. Katherine then asks Bevis about the waste chute incident before Bevis is ordered to throw the body away.

Chapter 17: The Pirate Suburb

Later, in the night, Tunbridge Wheels finds prey and tears up the Traction Town, kills the elderly and disabled, and makes slaves out of the young. Tom and Hester watch in horror before they meet the mayor of Tunbridge Wheels, Chrysler Peavey, whom Hester knows. Hester tries to talk to Chrysler, but the mayor orders Janny Maggs to take them to The Gut. Tom pleads with Chrysler and Chrysler lets Tom and Hester go, because Tom has a London (British) accent.

Tom and Hester meet Janny Maggs, Thick Mungo, Stadtsfesser Zeb, Pogo Nadgers, Zip Risky, "and the Traktiongrad Kid." Chrysler asks Tom to teach them proper etiquette. 

Chapter 18: Bevis

Three days later, London catches Slavic-speaking Traction Cities as prey. During the celebration, Herbert Melliphant sets off a firework in the London Museum and he is demoted from First Class Apprentice to Third Class Apprentice. Hebert plans to claw his way through the Rankings.

Katherines does not party that night. She is still thinking about Section Sixty when another three days pass by and she receives a note for her meet "at Pete's Eats in Belsize Park, Tier Five today at 11 am."

She goes to Pete's Eats and Bevis introduces himself to Katherine at a table. They talk about the Waste Chute incident and about Dr. Twix's Stalkers and experiments. As both leave, Katherine begs him to help unravel MEDUSA's mystery.

Chapter 19: The Sea of Khazak

Chrysler looks for Tom and when he finds him, he shows Tom the Sea of Khazak.

It takes two weeks for Tunbridge Wheels to make it through the Sea of Khazak. During that time, Tom realizes that Municipal Darwinism (a form of Darwinism, but in the Mortal Engines series sense) isn't what it seems. Chrysler takes a liking to Tom "like the son I never had."

The next day, Tunbridge Wheels reaches The Black Island in the middle of the Sea of Khazak. A deflated Airhaven is there, repairing it's floating gear. Chrysler and his band plan to plunder Airhaven.

Airhaven is still inflating it's floating gear when Chrysler's band reaches The Black Island's shore. Tom tell Chrysler about Anna Fang and Chrysler tells him that Anna Fang is "one of the Anti-Traction Leage's top agents." As they get closer to the shore, Hester calls out the phrase "It's a trap!" before Tunbridge Wheels is destroyed by rockets by natives. Chrysler attempts to take Tom and Hester with him onto a boat to The Black Island.

Chapter 20: The Black Island

Shrike has made it to The Black Island and continues hunting Tom and Hester.

Chrysler and the band have made it onto The Black Island. Chrysler reveals his plan to plunder Airhaven, use the floating Town to drop onto a Traction City and seize the city. When the band isn't looked, Tom and Hester talk about Anna Fang and Tom realizes Hester's anger is a cover-up for the real Hester: "the kind, shy Hester peeping from behind the grim mask." Chrysler catches them talking to each other and howls at them to move.

Shrike finds a destroyed Tunbridge Wheels and sees Hester and Tom aren't in the wreckage. He still continues to find the teens.

At night, Airhaven is ready to go back into the sky. Thick Mungo hisses they're late and Chrysler says that Airhaven is still weak for the moment. Suddenly, Janny, Thick, and a guy named Mr. Ames suddenly shoot Chrysler with their guns before Shrike finally catches up to Tom and Hester.

Chapter 21: In the Engineerium

London is eating a town called Panzersatdt-Bayreuth. During the catch, the public goes wild over the supplies and the Beefeaters have to calm them down.

Katherine and Bevis are in an elevator to the Engineerium. Before that, Katherine was looking up Hester Shaw in "A Complete Catalog of the London Museum" and only finds Pandora Shaw's name in it while Bevis was getting her disguise ready. Bevis and Katherine then get to the Engineerim, a black glass and obsidian-made place with silver globes hanging around for light. The seats are stadium-esque metal benches and the only way to get to the seats in a monorail. As soon as they take their seats, the presentation begins. Cromes reveals MEDUSA during it and his plan to get bigger prey and run over the Anti-Tractionist League. All the Engineers agree with him and Katherines runs from her seat. Bevis follows her and she realizes her father was lying as MEDUSA splits open the top of St. Paul's Cathedral, ready to fire.

Chapter 22: Grike

Janny, Thick, and Mr. Ames try to shoot Shrike with their guns, but it is no use. Shrike chokes Janny to death, spikes Mr. Ames as the pirate tries to flee, and cuts off Thick's head. Hester yells at Tom to run, but the Stalker cuts off their escape. Shrike tells Hester that when she dies, he will make her a Stalker. Hester laughs "a strange, mad, terrible sound that set Tom's teeth on edge" as Tom wriggles Thick's sword out and she asks him to spare her. Shrike denies and says he can spare Tom. Tom then slashes Shrike with Thick's sword, killing the Stalker. Hester hisses why Tom killed Shrike and Tom says that she was going to be turned into a Stalker. Hester says that she never wanted to be Tom's friend and "I'm already a monster!" As Hester storms away, Tom says what she really is, but it stops when he sees Airhaven floating above in the sky, horseback riders approaching them, and MEDUSA firing in the distance.

Chapter 23: MEDUSA

Katherine and Bevis run from the Engineerium as soon as an Engineer sees that they are fake Engineers. As they flee, Katherine sees Chudleigh Pomeroy on "Paternoster Square" and calls to him. MEDUSA is about to fire on Panzersatdt-Bayreuth. Katherine asks if he could take her home and Bevis to The Gut. Chudleigh says that Bevis can't go back to The Gut and that he'll take him to the London Museum to stay. Suddenly, MEDUSA strikes Panzerstadt-Bayreuth and there is cheering in London.

Part 2

Chapter 24: An Agent of the League

When MEDUSA is done firing and the horseback riders try to kill them, Tom and Hester were on Tunbridge Wheels when they got to The Black Island. Suddenly, Anna Fang speaks The Black Island language to prevent the natives from killing Tom and Hester. Tom sees that Anna has the sigil of the Anti-Traction League, "a bronze badge in the shape of a broken wheel", pinned on her shirt. Anna mentions that Nils and Yasmina went looking for Tom and Hester after the Airhaven Incident and thought they were dead. Anna brings Tom to Physician Ibrahim Azghul to be treated. Tom passes out as someone helps him eat mutton stew. Anna then wakes Tom up and Tom explodes about how Anna is a traitor. Anna says she is not a traitor and says she will take him and Hester to Shan Guo. Tom says that Hester hates him and Anna says she likes Tom.

Chapter 25: The Historians

At London, it is raining hard and Magnus Crome is standing outside with an apprentice holding an umbrella for him. He will not go anywhere without Stalkers being his new bodyguards. Dr. Vambrace finds Magnus and says that Pazerstadt-Bayreuth is destroyed. Magnus still insists on going to the Shield Wall, the wall the protects the Anti-Traction League and is the bridge between Europe and Asia.

Katherine walks across the remains of the celebrations and enters the London Museum. She finds Chudleigh Pomeroy in his office and asks if she can see Bevis. He says yes and she sees Bevis along with some other Historians. They are Dr. Arkengarth, Dr. Karuna, Professor Pottie Pewtertide, Clytie Potts, Norman Nancarrow, and Moira Plym. The people in the room talk about Magnus' plan and MEDUSA.

Chapter 26: Batmunkh Gompa

Anna, Tom, and Hester fly in the Jenny Haniver to Shan Guo. On the way they talk about MEDUSA and they stop at Peripatetiapolis. Tom hears about MEDUSA from the people there and buys Hester a red silk shawl for herself (since she doesn't want to be seen most of the time). The band keeps flying and on the next day, Anna gives herself, Tom, and Hester red balls of "Powdered betel nut... mixed with some dried leaves from Nuevo-Maya [South America]. They help at these high altitudes." For three days, Anna, Tom, and Hester are in the Jenny before they make it to Shan Guo and the Shield Wall. Shan Guo is in "the Mountains of Heaven" past "great Zhan Shan, tallest of earth's new mountains". The city they are at in "Batmunkh Gompa... The City of Eternal Strength." Anna takes Tom and Hester to the Governor's Palace, which is in an ancient monastery, to talk to Governor Ermene Khan.

As the band tries to talk to Ermene, the Governor is looking "down toward the lake of Batmunkh Nor" while taking pride in his city. The people argue about attacking London, in which Tom gets angered by it and Anna tells him to leave. Tom sits on a stone bench outside and after the meeting, news of MEDUSA is spread in Batmunkh Gompa. Some of the people see Tom as a hero. Tom walks his way around the city and finds the "Street of Weavers", where woven baskets are sold. In that place, Tom finds Valentine disguised as a holy man there.

Chapter 27: Dr. Arkengarth Remembers

As London wheels to Shan Guo, Katherine stays in the London Museum. Also as the days go on, Katherine finds herself falling in love with Bevis. Bevis is also helping out in the Museum and Katherine is trying to find things in it found by her father. One day, Dog, Katherine's pet wolf, walks into the section about animals and Dr. Arkengarth is in it. Dr. Arkengarth talks about the blue whale hanging on the ceiling that Pandora Shaw found and Katherine and the Historian talk about Pandora. Katherine then figures out that Hester is Pandora Shaw's daughter.

Chapter 28: A Stranger in the Mountains of Heaven

Tom sees Valentine pretending to be a holy man and begins chasing him. Valentine, out of fear of being caught, runs. Tom then accidentally follows a real holy man and not Valentine during the chase. Anna, Khora, Sathya (the Keralan girl from the meeting in part 2, chapter 26) catch up to Tom and wonder about Valentine's whereabouts. Tom says he has to tell Hester, but Anna says no. They then decide to turn on the alarm. Tom then begins looking for Hester and London suddenly takes down the Air Fleet and the Shield Wall with MEDUSA. As Tom continues looking for Hester, he finds Thaddeus and Anna in a sword duel, with Anna being killed by Thaddeus.

Chapter 29: Going Home

Thaddeus escapes by jumping off a cliff and into the 13th Floor Elevator. Tom starts to go after him, but the airship flies off. Hester finds Tom and she says she should've fought Valentine. Hester and Tom then decide to fly the Jenny Haniver to London to finish what Hester started at the beginning of the novel.

Chapter 30: A Hero's Welcome

The 13th Floor Elevator lands on London and Katherine watches her father and Magnus Crome exit the airship. When Thaddeus gets into his estate and greets Katherine in her bedroom, she confronts him about what he did to Hester and Pandora. Thaddeus then tells Katherine he tried to murder Hester and Pandora for her. He then tells about how he met Pandora and found out about MEDUSA and the murder 7 years ago. Thaddeus then tells Katherine that Hester is her half-sister. Katherine finally figures out her father, Hester, and she runs away from him while the news of Thaddeus' return is shared in London.

Chapter 31: The Eavesdropper

People in London are chattering about the new Hunting Grounds in Asia.

Katherine enters the London Museum and doesn't see Bevis there. She asks an unnamed Herbert Melliphant where Bevis is and Herbert tells her he and Norman are in the storerooms. As soon as Katherine finds Bevis, she hugs him and tells him they have to stop Thaddeus and Magnus that night. Katherine and Bevis talk about their plan to use a bomb, but Herbert Melliphant is secretly spying on them.

Thaddeus is looking for Katherine and when Pewsey and Gench spot her in the London Museum, Thaddeus demands to be taken to her.

Magnus Crome is eating dinner in his office when Herbert Melliphant come into the office and tell Magnus about the bomb.

Chapter 32: Chudleigh Pomeroy Sees It Through

Katherine and Bevis make the bomb with Bevis' knowledge of making things and chemistry. Katherine says she can plant the bomb and Bevis says he wants to go with her. In response, Kathrine kisses Bevis and Dog seems a little grumpy about it. Suddenly, Dr. Vambrace and Engineer soldiers come into the Museum and storm their way to where Katherine is. Chudleigh Pomeroy is furious and when the solider enters, Dog growls at them. One of the soldiers then shoots Dog and the wolf is dead. Katherine and Bevis are forced to hand over the bomb and the soldiers takes Katherine and Bevis away from each other (Katherine to Top Tier, Bevis to The Gut).

Thaddeus enters his car and Pewsey drives him to the Guildhall. Thaddeus plans on how to kill Hester.

The soldiers lead Katherine and Bevis into the "Weapons & Warfare Gallery", where the Historians are holding ancient weapons, ready to kill. Chudleigh says that the Engineers are on Historian ground and that Katherine and Bevis need to be released. Dr. Vambrace says that the Engineers will rule London and the Historians will be exterminated. A fight breaks out with the weapons, allowing Bevis and Katherine to escape. Bevis quickly joins the fight when he finds an old shotgun and Katherine sees he that can kill. When the battle is over, Dr. Arkengarth and Dr. Weymouth are the only Historians dead and that Dr. Vambrace and the Engineer soldiers are dead. There are other Engineer soliders who are guarding the museum and raised the soldier alarm, as Clytie then points out. Chudleigh then plans to sneak Katherine and Bevis into St. Paul's Cathedral by a walkway known as "the Cat's Creep."

Chapter 33: Wine and Nibbles and the Dawn of a New Era

As Tom and Hester fly the Jenny Haniver to London, the teens find that Anna was rich from her expeditions. As Tom tries to navigate the Jenny, Hester finds the weapons she needs: "a heavy black pistol and a long, thin-bladed knife."

That night, all the Guilds mingle with each other and try Nimmo's snacks he made out of human feces. As soon as Thaddeus arrives on the scene, people greet him. Magnus greets him and tells him about the rebel Historians and how Katherine is there. Thaddeus wants to see her, but Tier Two (one of the top tiers) is off limits during the party.

Chudleigh helps Katherine and Bevis through the Cat's Creep and Katherine asks Chudleigh to come with her. The Historian says no and says she has Thaddeus' gift making people follow him.

Tom and Hester reach London and see that MEDUSA is about to be fired. Hester says she knows that Thaddeus is down there and deserves his death.

Katherine and Bevis walk up stairs inside London to Top Tier, the highest of the Tiers on London. 

As Tom and Hester reach the boarding area, the crew wants to know their code and why their there. Tom says "London Airship GE47... We're bringing Grike back to the Engineerium." Hester and Tom tell each not to die before Hester jumps off of the Jenny and onto London.

Magnus and Thaddeus find the Jenny Hanvier in the sky and think that Anti-Tractionists will ruin the party.

Chapter 34: Idea for a Fireworks Display

As Tom gets near London, a rocket from the 13th Floor Elevator launches at Tom and the Jenny Haniver, totaling the gondola.

Magnus is about to fire MEDUSA and Thaddeus tells him that shooting at the Shield Wall will destroy cities and people. Magnus takes this a traitorous and says that the Engineers will rule the world.

Hester is cautious about getting past the Stalkers.

Katherine and Bevis get into Tier One and Top Tier and see the rockets pummel the Jenny Haniver. Katherine and Bevis hug each other before departing to destroy MEDUSA.

Tom is severely injured, but he gets back in the pilot's seat and fires rockets at the 13th Floor Elevator, killing Pewsey and Gench in the process as the airship tumbles down to London.

Katherine is on Tier One when the 13th Floor Elevator falls towards London. At the last second, Bevis pushes her out of the way, killing himself while saving Katherine. A Historian notices Katherine and tell her Thaddeus is at St. Paul's Cathedral and not in the explosion.

Hester is running to the Guildhall when the 13th Floor Elevator crashes. She looks up at the sky and suddenly worries about Tom. She is then surrounded by Stalkers.

Chapter 35: The Cathedral 

Tom is brutally injured in the Jenny Haniver. When he looked up, he sees he is far from the London (the wind blew him) and sees that MEDUSA is about to be fired.

Katherine walks into St. Paul's Cathedral and sees Magnus and Thaddeus standing in front of MEDUSA. As the machine is about to fire, Thaddeus quickly changes sides and Magnus says he can change sides later. As a guy named Dr. Chubb puts in the coordinates, Dr. Twix comes in with Stalkers following her. Kathrine sees Hester, arrested by the Stalkers, thrown in front of Magnus and Thaddeus. Thaddeus uses his sword to kill Hester, but Katherine jumps in the way, killing her and saving Hester. As MEDUSA's power begins to build up, Magnus says "I only wanted to make London strong!"

Chapter 36: The Shadow of Bones

Hester gets out of the Guildhall and looks up to the to find Tom. She does.

Tom looks down from the Jenny and the first thing he sees is Hester.

As Hester jumps onto the Jenny, Thaddeus yells at them "Hester! Tom! Fly! Save yourselves!" Tom wonders where Katherine is.

In The Gut, London's engines suddenly stop moving permanently. In the London Museum, the Historians cheer over their victory of fighting the Engineers.

Thaddeus watches Hester and Tom fly away in the Jenny as MEDUSA explodes on London, killing everyone.

Chapter 37: The Bird Roads

Hester watches London fall from MEDUSA with Tom on the Jenny Haniver, which survived the explosion. In the pilot's seat, Tom breaks down on how he brought London's demise. but Hester comforts him by"[putting] her arms around him and pulled him close, nuzzling the top of his head, shyly kissing away the blood from the fresh wound between his eyebrows, hugging him tight until the dying weapon had spent itself and the first gray daylight crept across the plain." She then tells them they will go to Batmunkh Gompa, but Tom says no. Hester sighs and promises him that they will go The Black Island, repair the Jenny Haniver there, and stay together.

Borrowed: 07/06/2018-07/26/2018

Originally published: 07/17/2018; edited: 05/20/2021 (grammar fixes), 05/26/2021 (grammar and sentence fixes), 06/07/2021 (grammar fixes)