MIA WASN'T SURPRISED when the snake people arrived.

When the ship docked at the harbor in Piraeus, on the outskirts of Athens, she stared out at the horizon. Somewhere nearby — past those rows of cruise ships, past those hills crowded with buildings — they would find the Acropolis. Today, one way or another, their journey would end.

But that didn't mean she could relax. Any moment, a nasty surprise might come flying out of nowhere.

As it turned out, the surprise was three dudes with snake tails instead of legs.

Mia and Piper were on watch while the rest of the crew geared up for combat — checking their weapons and armor, loading the ballistae and catapults. She spotted the snake guys slithering along the docks, winding through crowds of mortal tourists who paid them no attention.

"Um . . . Annabeth?" Piper called. Mia resisted the urge to roll her eyes.

Annabeth and Percy came to their sides.

"Oh, great," Percy said. "Dracaenae."

Annabeth narrowed her eyes. "I don't think so. At least not like any I've seen. Dracaenae have two serpent trunks for legs. These guys just have one."

"You're right," Percy said. "These look more human on top, too. Not all scaly and green and stuff. So do we talk or fight?"

Mia was tempted to say fight. She liked fighting things. Fighting things was good.

The snake man in the lead held his head high. His face was chiselled and bronze, his eyes black as basalt, his curly dark hair glistening with oil. His upper body rippled with muscles, covered only by a Greek chlamys — a white wool cloak loosely wrapped and pinned at the shoulder. From the waist down, his body was one giant serpent trunk — about eight feet of green tail undulating behind him as he moved.

In one hand he carried a staff topped with a glowing green jewel. In his other, he carried a platter covered with a silver dome, like a main course for a fancy dinner.

The two guys behind him appeared to be guards. They wore bronze breastplates and elaborate helmets topped with horsehair bristles. Their spears were tipped with green stone points. Their oval shields were emblazoned with a large Greek letter K — kappa.

They stopped a few yards from the Argo II. The leader looked up and studied the demigods. His expression was intense but inscrutable. He might have been angry or worried or terribly in need of a restroom.

"Permission to come aboard." His voice was strangely raspy. Mia knew from experience that raspy voices weren't a good thing in this economy.

"Who are you?" Piper asked.

He fixed his dark eyes on her. "I am Kekrops, the first and eternal king of Athens. I would welcome you to my city." He held up the covered platter. "Also, I brought a Bundt cake."

Mia glanced at her friends. "A trick?"

"Probably," Annabeth said.

"At least he brought dessert." Percy smiled down at the snake guys. "Welcome aboard!"

Kekrops agreed to leave his guards above deck with Buford the table, who ordered them to drop and give him twenty push-ups. The guards seemed to take this as a challenge.

Meanwhile, the king of Athens was invited to the mess hall for a 'get to know you' meeting.

"Please take a seat," Jason offered.

Kekrops wrinkled his nose. "Snake people do not sit."

"Please remain standing," Leo said. He cut the cake and stuffed a piece in his mouth before Mia could warn him it might be poisoned, or inedible for mortals, or just plain bad.

"Dang!" He grinned. "Snake people know how to make Bundt cake. Kind of orangey, with a hint of honey. Needs a glass of milk."

"Snake people do not drink milk," Kekrops said. "We are lactose-intolerant reptiles."

"Me, too!" Frank said. "I mean . . . lactose intolerant. Not a reptile. Though I can be a reptile sometimes—"

"Anyway," Hazel interrupted, "King Kekrops, what brings you here? How did you know we'd arrived?"

"I know everything that happens in Athens," Kekrops said. "I was the city's founder, its first king, born of the earth. I am the one who judged the dispute between Athena and Poseidon, and chose Athena to be the patron of the city."

"No hard feelings, though," Percy muttered.

Annabeth elbowed him. "I've heard of you, Kekrops. You were the first to offer sacrifices to Athena. You built her first shrine on the Acropolis."

"Correct." Kekrops sounded bitter, like he regretted his decision. "My people were the original Athenians — the gemini."

"Like your zodiac sign?" Percy asked. "I'm a Leo."

"No, stupid," Leo said. "I'm a Leo. You're a Percy."

"Will you two stop it?" Mia rolled her eyes. "He means gemini like doubled — half man, half snake. That's what his people are called. He's a geminus, singular."

"Yes . . ." Kekrops leaned away from her as if she somehow offended him, which made her narrow her eyes. Rude. "Millennia ago, we were driven underground by the two-legged humans, but I know the ways of the city better than any. I came to warn you. If you try to approach the Acropolis aboveground, you will be destroyed."

Jason stopped nibbling his cake. "You mean . . . by you?"

"By Porphyrion's armies," said the snake king. "The Acropolis is ringed with great siege weapons — onagers."

"More onagers?" Frank protested. "Did they have a sale on them or something?"

"The Cyclopes," Hazel guessed. "They're supplying both Octavian and the giants."

Percy grunted. "Like we needed more proof that Octavian is on the wrong side."

"That is not the only threat," Kekrops warned. "The air is filled with storm spirits and gryphons. All roads to the Acropolis are patrolled by the Earthborn."

Frank drummed his fingers on the Bundt cake cover. "So, what, we should just give up? We've come too far for that."

"I offer you an alternative," said Kekrops. "Underground passage to the Acropolis. For the sake of Athena, for the sake of the gods, I will help you."

"What's the catch?" Piper asked.

Kekrops turned to her. "Only a small party of demigods — no more than three — could pass undetected by the giants. Otherwise your scent would give you away. But our underground passages could lead you straight into the ruins of the Acropolis. Once there, you could disable the siege weapons by stealth and allow the rest of your crew to approach. With luck, you could take the giants by surprise. You might be able to disrupt their ceremony."

"Ceremony?" Leo asked. "Oh . . . like, to wake Gaia."

"Even now it has begun," Kekrops warned. "Can you not feel the earth trembling? We, the gemini, are your best chance."

Mia heard eagerness in his voice — almost hunger.

Percy looked around the table. "Any objections?"

"Just a few," Jason said. "We're on the enemy's doorstep. We're being asked to split up. Isn't that how people get killed in horror movies?"

"Also," Percy said, "Gaia wants us to reach the Parthenon. She wants our blood to water the stones and all that other psycho garbage. Won't we be playing right into her hands?"

Kekrops's offer made sense. At least, it sounded like the least suicidal option. But Mia was certain the snake king was hiding his true intentions.

Weren't snakes charmed by music or something? Or was that something different? Mia didn't know, but when she felt Piper's eyes on her — after Sparta, Piper and Annabeth had become a duo that either worked too well together or not at all, and when the latter happened, they'd look to Mia for advice because she's amazing, obviously — she discreetly hummed a song from a play she'd watched under her breath.

Luckily, Piper got the message. She began to sing a song.

Kekrops stared at her in wonder. He began to sway.

Everyone listened, transfixed, as she finished the first verse. No one spoke for a count of five.

"Pipes," Jason said, "I had no idea."

Bro, if Mia somewhat knew and Jason didn't, what does that say about him?

"That was beautiful," Leo agreed. "Maybe not . . . you know, Calypso beautiful, but still . . ."

Piper kept the snake king's gaze. "What are your real intentions?"

"To deceive you," he said in a trance, still swaying. "We hope to lead you into the tunnels and destroy you."

"Why?" Piper asked.

"The Earth Mother has promised us great rewards. If we spill your blood under the Parthenon, that will be sufficient to complete her awakening."

"But you serve Athena," Piper said. "You founded her city."

Kekrops made a low hiss. "And in return the goddess abandoned me. Athena replaced me with a two-legged human king. She drove my daughters mad. They leaped to their deaths from the cliffs of the Acropolis. The original Athenians, the gemini, were driven underground and forgotten. Athena, the goddess of wisdom, turned her back on us, but wisdom comes from the earth as well. We are, first and last, the children of Gaia. The Earth Mother has promised us a place in the sun of the upper world."

"Gaia is lying," Piper said. "She intends to destroy the upper world, not give it to anyone."

Kekrops bared his fangs. "Then we will be no worse off than we were under the treacherous gods!"

He raised his staff, but Piper launched into another verse.

The snake king's arms went limp. His eyes glassed over.

Piper sang a few more lines, then she risked another question: "The giants' defenses, the underground passage to the Acropolis — how much of what you told us is true?"

"All of it," Kekrops said. "The Acropolis is heavily defended, just as I described. Any approach aboveground would be impossible."

"So you could guide us through your tunnels," Piper said. "That's also true?"

Kekrops frowned. "Yes . . ."

"And if you ordered your people not to attack us," she said, "they would obey?"

"Yes, but . . ." Kekrops shuddered. "Yes, they would obey. Three of you at most could go without attracting the attention of the giants."

Annabeth's eyes darkened. "Piper, we'd be crazy to try it. He'll kill us at the first opportunity."

"Yes," the snake king agreed. "Only this girl's music controls me. I hate it. Please, sing some more."

Piper gave him another verse.

Leo got into the act. He picked up a couple of spoons and made them do high kicks on the tabletop until Hazel slapped his arm.

"Mia or I should go," Hazel said, "if it's underground."

"Never," Kekrops said. "A child of the Underworld? My people would find your presence revolting. No charming music would keep them from slaying you."

"Or we could stay here," Mia smirked, not bothering to hide it. She hated snakes. Yes, she is one, but still, she was glad not to spend her time around them as much as she could.

"Me and Percy," Annabeth suggested.

"Um . . ." Percy raised his hand. "Just gonna throw this out here again. That's exactly what Gaia wants — you and me, our blood watering the stones, et cetera."

"I know." Annabeth's expression was grim. "But it's the most logical choice. The oldest shrines on the Acropolis are dedicated to Poseidon and Athena. Kekrops, wouldn't that mask our approach?"

"Yes," the snake king admitted. "Your . . . your scent would be difficult to discern. The ruins always radiate the power of those two gods."

"And me," Piper said at the end of her song. "You'll need me to keep our friend here in line."

Jason squeezed her hand. "I still hate the idea of splitting up."

"But it's our best shot," Frank said. "The three of them sneak in and disable the onagers, cause a distraction. Then the rest of us fly in with ballistae blazing."

"Yes," Kekrops said, "that plan could work. If I do not kill you first."

"I've got an idea," Annabeth said. "Frank, Hazel, Leo . . . let's talk. Piper, can you keep our friend musically incapacitated?"

Piper started a different song. Annabeth, Leo, Frank and Hazel left to talk strategy.

"Well." Percy rose and offered his hand to Jason. "Until we meet again at the Acropolis, bro. I'll be the one killing giants."