Master Chief traversing a forest on his trek towards the UNSC Infinity.

Cortana: Stay low; recon sortie heading this way.

John hides himself beneath a tree as several Phantoms and Banshees speed towards the Infinity. The Didact's Cryptum holds position above the ship, sending out periodic scans over the hull.

Cortana: The ship looks intact.
Master Chief: Something tells me that's only because the Didact wanted it that way.
Commander Thomas Lasky (COM): This is Lasky to UNSC Infinity. We're up to our necks in bad guys down here! Does anyone read?

He knew Lasky for a long time since Corbulos Academy Rescue.

Master Chief: This is Sierra-117 of the UNSC Forward Unto Dawn. We're on station, ready to assist.
Lasky (COM): Negative copy, sounded like you said "Forward Unto Dawn"? Come again-

The transmission breaks up, leaving only static.

Cortana: Signal's bouncing in and out; I can't clean it up.
Master Chief: Light up their friend-or-foe tags; we're gonna need something to zero in on.

Master Chief looks on as the Cryptum continues to scan the Infinity. He rushes to the Infinity as he's fighting with the Covenant and Promethean Knights while identifying their IDs. He used his rifle to shoot them down then proceeded down the hills then he grabbed DMR and shot them down. He continued to sprint to the point.

Master Chief arrives at the entrance to a Forerunner structure, hidden beneath thick foliage. A stack of UNSC crates and weaponry lies outside the doorway, along with an IFF tag. Unlike the last tags, there are no nearby corpses.

Cortana: That's the friend-or-foe tag, but where's whoever it belongs to?

John accesses the IFF tag record.

Marine #3 (recording): XO! We've got it!
Palmer (recording): Move, move, move!
Marine #4 (recording): Light's green!
Marine #3 (recording): C'mon, crank it!
Lasky (recording): Palmer, get your folks inside!
Palmer (recording): Yes, sir! Fours, go!
Several NAV points appear behind the entrance.

Cortana: Multiple IDs - Chief, they're friendlies!

Two SPARTAN-IVs exit as soon as the doorway opens, led by Sarah Palmer. They secure the area behind John as he observes them. Lasky approaches John.

Lasky: Afraid we'll have to give you an IOU on that welcome home party.
The Commander shakes the Chief's hand.

Lasky: Tom Lasky, First Officer of Infinity. Never thought I'd see you again.
Palmer: Seal her up!

Palmer turns around and approaches John, smiling.

Palmer: I thought you'd be taller.

John stares at her wordlessly. Behind them, a radio sputters to life. The transmission is laced with static.

Del Rio (COM): ...ground forces are ordered to return to Infinity immediately!
Marine: Commander! Radio's hot!

John and Lasky walks back inside, the SPARTAN-IVs following shortly after. The entrance seals itself behind them.

Del Rio (COM): ...respond to comm...on what frequency? What frequency, dammit?!

Lasky kneels down next to the radio, while John and Palmer stands guard.

Lasky: Infinity, this is Commander Lasky. Pelican recon teams are down - repeat, all birds are down! We've got numerous casualties and require immediate assistance, over!
Del Rio (COM): Finally... Did you get the coordinates to that gravity well?
Lasky: Affirmative, sir, but we're going to need a bus out of here-
Del Rio (COM): Make it happen!
The transmission cuts off.

Cortana: You were sent on a scouting run in the middle of an attack on the ship...
Lasky: The Captain thought Infinity could provide us cover and hold off the attack at the same time.

Palmer approaches the XO, frowning.

Palmer: Sir...we'll never get the wounded back to the ship on foot.

Lasky stands up, facing the Chief.

Lasky: I don't know if it's too soon to ask you for a favor, but...we're going to run out of breathing room here real quick. I don't suppose you're any good at clearing LZs?
Master Chief: On occasion. I'll send out an all-clear once the area's secured.

Master Chief accompanied by Marines they engaged in the firefight with Promethean Knights after engaging a small Promethean contingent, the squad moves forward.

Marine: I can see the door!

The squad clear the area, only to find a locked exit. Several dead Marines lie nearby, having failed to hold off the Prometheans.

Cortana: "The marines got trapped trying to get through these doors. Look for an interface!"
John uploads Cortana into a nearby pedestal.

Cortana: These doors open into a cave system with a space large enough for an LZ. Hold them off long enough for me to open the doors!

The UNSC forces defend the hill top. Marines man the machine gun turrets on the top of the hill and fire at the assaulting Prometheans, who send out wave after wave of infantry at the defenders. He grabbed the railgun and fires at Prometheans.

Master Chief: Cortana? How close are we?
Cortana: (rampant) You do your job and I'll do mine, okay?!

The majority of the Prometheans are eliminated. The Marines stay behind as John moves into a small cavern.

Cortana: Got it! Passageway's unlocked. Come and get me!

John retrieves Cortana and enters the cave. His HUD is again distorted by static as Cortana deteriorates.

Cortana: I'm sorry about back there. That hatch's security was more difficult than I expected.
Master Chief: It's alright...
Cortana: It's not alright. Nothing about it is alright.

The tunnel leads to an open cavern. A Promethean Knight stands guard at the exit.

Cortana: Knight! Wait...what's he doing?
The Knight appears to be giving out orders to nearby Unggoy.

Master Chief: Covenant?
Cortana: They're working with the Prometheans?

John attacks the Prometheans and Covenant remnant troops, which include a significant number of Unggoy, Kig-Yar, and even a Kig-Yar Sniper.

Cortana: I'm shocked how quickly the Didact has unified these Covenant!
Phantoms arrive to drop off more Covenant troops, while several more Knights teleport into the cavern.

Cortana: Knights!

John eventually clears the area. A Pelican approaches the landing zone, opening its back hatch.

Cortana: Cortana to Lasky. LZ is secured.
Lasky (Video COM): Roger that, Cortana. I'll get you the coordinates for the-
Del Rio (COM): Mayday! Mayday! Code Red! Hostile elements attempting to gain entrance to the Infinity bridge!
Officer #1 (COM): They're outside the hatch!
Officer #2 (COM): Door's breached! Door's breached!
Del Rio (COM): All units, return to Infinity immediately! That's an order!
Lasky (Video COM): Chief, I'm redirecting the SPARTAN-IVs to rally point Alpha-Sierra-Foxtrot! Until we catch up, you have tactical command of the forward assault force. Rendezvous with those men and take back that ship!
Master Chief: Yes, sir.

Lasky (Video COM): Good luck, Chief. Lasky out.

John enters the Pelican as it took off to Infinity.

Pelican Pilot (COM): This is Pelican 595. We have the Chief onboard and are outbound for rally point Alpha-Sierra-Foxtrot.

The Pelican drops John off in an open canyon, choked with dust and debris from the crashed Infinity. SPARTAN-IVs are engaging nearby Covenant infantry.

Cortana: Weapons free, Chief! Let them have it!"

He uses his DMR once again to shoot them down then he boards a nearby Scorpion.

Cortana: We're good to go, Chief. Let's show these Spartans how it's done.

SPARTAN-IV: "Ground teams, be advised: the Master Chief is on the field. Advancing."
Two SPARTAN-IVs board the nearby Warthog, while the rest ride shotgun on the Scorpion's treads. The assault force pushes through heavy Covenant fortifications, including Wraiths, Ghosts, deployable lookout towers, and infantry.

Lasky (COM): 117, Lasky. We're touching down just north of your position. Proceed to starboard hangar 2-19, and we'll link up with you there.

The assault force eventually arrives at a route leading down to a cargo elevator. Three SPARTAN-IVs are defending it against a Wraith and several Ghosts. The Chief provides assistance, disposing of remaining hostiles in the area.

Cortana: Commander, the hangar bay doors are sealed tight.
Lasky (COM): Roger, Cortana. We'll find a way inside and free up one of the mooring platforms. XO out.

The Chief enters the platform just as a large chunk of debris collapses, blocking the exit. The elevator seals itself and takes him up to hangar 2-19. More Spartans are combating Covenant forces, including a pair of Mgalekgolo.

Lasky (COM): Secure the bay, and I'll release the lockdown on the ship.

System (PA): Alert - hull breach on Deck 13, Sector 5. Deck 25, Sector 12. Deck 131, Sector 7. Deck 270. Deck 895.

Together, the Spartans clear the hangar of Covenant troops.

Del Rio (Video COM): Master Chief, this is Captain Del Rio. Lasky just radioed - you picked a helluva time to rejoin us!
Master Chief: Sir, what's our status?
Del Rio (Video COM): That satellite took down the ship's defenses and is extracting data from the ship's mainframes as we speak.
Master Chief: Can we break the connection?
Del Rio (Video COM): Main point of contact's on the ship's upper hull; the fastest route is through the maintenance causeway. There's a Mantis docked inside the door. Take it. You'll need the extra firepower.

A doorway on the right opens, leading into a large chamber.

Cortana: Well, the Captain promised you firepower. This sure seems like an appropriate use for it. Look for the Mantis controls.

Master Chief activates a control panel.

MANTIS ACTIVATED

>OPEN<

System (PA): Warning - operation of the Mantis Armored Defense System is prohibited without prior approval.
A circular plate in the room's center splits in two, and a Mantis emerges from below. John boards the bipedal mech.

Cortana: The hatch to the maintenance causeway is jammed. Let's do something about it.

John, using the Mantis' armaments, destroys the hatch. He engages the Covenant and Prometheans occupying the maintenance causeway.

Cortana: Chief, Infinity TAC-COM is reporting additional contacts on the outer deck. Pick it up, Chief!
Cortana: We're not doing the Infinity any good down here if the Didact's linked in from the outer hull.
Cortana: Chief, we can't let the Didact get access to the Infinity's data stores. Let's get topside!
System (PA): Condition Red - all personnel to emergency stations. Condition Red - all personnel to emergency stations.

John pushes on, wiping out Covenant forces infesting the causeways. Promethean Knights regularly phase in, but are easily killed by the Mantis' weapons.

System (PA): Warning - UNSC Infinity has descended below minimum safe attitude. Internal atmospheric pressure unstable.
John reaches the door to an elevator.

System (PA): Attention, Mass Deployment Bay vessels - emergency mooring procedure initiated. Bay doors will not respond to traffic control requests. Response crews are en route. Please avoid MDB F-959 until further notice.

John enters the elevator, eliminating a lance of panicking Unggoy.

Lasky (COM): Chief, it's Lasky. Come in.
Master Chief: Go, Commander.
Lasky (COM): We've identified several Covenant jamming devices on the outer hull.
Cortana: That might be how they're blocking the Infinity's defenses.
Lasky (COM): Exactly what we were thinking. Neutralize them, so we can get our guns back online and show that satellite we are more than just a big paperweight.
The elevator stops.

Cortana: We're on it, Commander. Cortana out.

John leaves the hallway and arrives at the upper hull. The Cryptum is hovering directly in front of the Infinity, scanning the ship's systems. Eight Covenant CRS-class light cruisers are holding position over the ship, sending swarms of Phantoms and Banshees against the Infinity's Pelicans. The ship's point-defense weaponry are all offline, courtesy of the three jammers lying on the far side of the area.

Cortana: I see the jammers, three of them. Shoot them down!
John destroys one of the jammers. The cannon behind the jammer activates and begins to fire at approaching Phantoms.

Cortana: First jammer disabled.
John destroys the second jammer. Another anti-air gun reactivates itself.

Cortana: That's two...
John destroys the last jammer. The point-defense autocannons are now fully operational.

Cortana: That's it - jammers neutralized!
Even more Phantoms arrive, sending waves of Covenant infantry against the Chief. Many Sangheili Rangers and Unggoy wielding fuel rod guns attack the Mantis. The Cryptum moves closer towards the ship.

Del Rio (COM): Del Rio to Master Chief. The rate that thing is searching our systems just doubled - I think it knows what you're up to.
Cortana: The Didact's not letting go without a fight.

More Phantoms land and deploy troops to attack John. By this point, the Infinity's missile batteries have been reactivated.

Cortana: Hold them off...

Banshees and Phantoms push on to attack the ship, but most of them are destroyed by the anti-air defenses. The rest are neutralized by John.

Cortana: Just a few more minutes!

The Infinity's defenses eventually cripple two of the light cruisers, setting them ablaze. The two ships begin to lose altitude.

Cortana: I'm still seeing targets. Finish them off!
John clears the hull of Covenant. Phantoms stop entering the area.

Cortana: That's how it's done.
Del Rio (COM): Captain Del Rio to Sierra-117. The MAC network's reading operational, but our EM relays are malfunctioning. You'll have to initiate the link manually.

He dismounts the Mantis and approaches the MAC network's control panel and activates it.

MAC CONTROLS

>ACTIVE<

Cortana: That's it! MAC controls restored!
The center MAC gun on the hull's platform reactivates and takes aim.

Del Rio (COM): Forward MAC batteries - get that damn orb away from my ship! All cannons, fire at will!

All of the Infinity's broadside defenses fire at Didact's Cryptum; a formation of Broadswords charges at the sphere, guns blazing. After taking several shots from the Onager, the Cryptum retreats into the jungle.

Cortana: It's working! The Didact's retreating
Del Rio (COM): Del Rio to Infinity, all hands. We are Condition Yellow...stand down. Section heads, report in; begin damage assessment.

The Infinity, damaged but intact, manages to take off. Captain Del Rio, Lasky, John, and Palmer has gathered in the bridge, with Cortana at the holotank.

Del Rio: What I want to know, people, is where the hell did those things come from?!

Cortana projects a hologram of a Knight on the table.

Cortana: It's possible that they're native to Requiem. Or...whatever counts as native for a Forerunner AI.
Del Rio: We've never seen this type of offensive reaction from any of the other installations.
John: Other installations?

The Captain turns to his XO, annoyed.

Del Rio: Mr. Lasky...

Lasky brings up a hologram of a Halo installation.

Lasky: Infinity's mission is to locate the remaining Halo rings, and establish permanent bases to study them for decommission.

The hologram shifts into an asteroid belt, with a UNSC facility built into the largest rock.

Lasky: We've got locations up and running around Installations 05 and 03, but...lately, they've run into some setbacks.
Del Rio: A science team got zapped excavating a Forerunner artifact. This...sensor data is all that was left.

The Captain brings up a new hologram: dozens of Forerunner glyphs arranged in a circular pattern, converging around the Didact's symbol.

Cortana: Interesting...these symbols are a derivation of the Forerunner glyph system.
Del Rio: And our geeks managed to pull some coordinates. I'll give you three guesses where it led.

Commander Palmer approaches Del Rio, handing over a tablet to him.

Palmer: Sir, Gypsy Company is prepped and ready to roll on your orders.
Del Rio: Thank you, Palmer. Mr. Lasky, you take point - I want boots on the ground in sixty.

The Chief is caught off-guard by Del Rio's orders.

Master Chief: Captain?
Del Rio: This is a First Contact scenario, Master Chief. Priority is to free Infinity from Requiem's gravity well and file a threat assessment back at FLEETCOM.
Cortana: You mean we're leaving?
Master Chief: Sir, Infinity drove the Didact back. He's vulnerable!

Del Rio: ...he isn't the only one.

The Captain glares at the Chief one last time before leaving.

Del Rio: You know, I'd think you, of all people, would appreciate the benefit of living to fight another day.

Del Rio departs from the bridge, leaving John and Cortana behind as they look at each other.

Master Chief (thoughts): Well I guess It's worth a shot.