He willed his hand to catch fire, and set it against the door.

His cabinmates gasped.

"Leo!" Nyssa cried. "You're a fire user!"

"Yeah, thanks," he said. "I know."

Jake Mason, who was out of his body cast but still on crutches, said, "Holy Hephaestus. That means-it's so rare that-"

The ma.s.sive stone door swung open, and everyone's mouth dropped. Leo's flaming hand seemed insignificant now. Even Piper and Jason looked stunned, and they'd seen enough amazing things lately.

Only Chiron didn't look surprised. The centaur knit his bushy eyebrows and stroked his beard, as if the group was about to walk through a minefield.

That made Leo even more nervous, but he couldn't change his mind now. His instincts told him he was meant to share this place-at least with the Hephaestus cabin-and he couldn't hide it from Chiron or his two best friends.

"Welcome to Bunker Nine," he said, as confidently as he could. "C'mon in."

The group was silent as they toured the facility. Everything was just as Leo had left it-giant machines, worktables, old maps and schematics. Only one thing had changed. Festus's head was sitting on the central table, still battered and scorched from his final crash in Omaha.

Leo went over to it, a bitter taste in his mouth, and stroked the dragon's forehead. "I'm sorry, Festus. But I won't forget you."

Jason put a hand on Leo's shoulder. "Hephaestus brought it here for you?"

Leo nodded.

"But you can't repair him," Jason guessed.

"No way," Leo said. "But the head is going to be reused. Festus will be going with us."

Piper came over and frowned. "What do you mean?"

Before Leo could answer, Nyssa cried out, "Guys, look at this!"

She was standing at one of the worktables, flipping through a sketchbook-diagrams for hundreds of different machines and weapons.

"I've never seen anything like these," Nyssa said. "There are more amazing ideas here than in Daedalus's workshop. It would take a century just to prototype them all."

"Who built this place?" Jake Mason said. "And why?"

Chiron stayed silent, but Leo focused on the wall map he'd seen during his first visit. It showed Camp Half-Blood with a line of triremes in the Sound, catapults mounted in the hills around the valley, and spots marked for traps, trenches, and ambush sites.

"It's a wartime command center," he said. "The camp was attacked once, wasn't it?"

"In the t.i.tan War?" Piper asked.

Nyssa shook her head. "No. Besides, that map looks really old. The date ... does that say 1864?"

They all turned to Chiron.

The centaur's tail swished fretfully. "This camp has been attacked many times," he admitted. "That map is from the last Civil War."

Apparently, Leo wasn't the only one confused. The other Hephaestus campers looked at each other and frowned.

"Civil War ..." Piper said. "You mean the American Civil War, like a hundred and fifty years ago?"

"Yes and no," Chiron said. "The two conflicts-mortal and demiG.o.d-mirrored each other, as they usually do in Western history. Look at any civil war or revolution from the fall of Rome onward, and it marks a time when demiG.o.ds also fought one another. But that Civil War was particularly horrible. For American mortals, it is still their bloodiest conflict of all time-worse than their casualties in the two World Wars. For demiG.o.ds, it was equally devastating. Even back then, this valley was Camp Half-Blood. There was a horrible battle in these woods lasting for days, with terrible losses on both sides."

"Both sides," Leo said. "You mean the camp split apart?"

"No," Jason spoke up. "He means two different groups. Camp Half-Blood was one side in the war."

Leo wasn't sure he wanted an answer, but he asked, "Who was the other?"

Chiron glanced up at the tattered bunker 9 banner, as if remembering the day it was raised.

"The answer is dangerous," he warned. "It is something I swore upon the River Styx never to speak of. After the American Civil War, the G.o.ds were so horrified by the toll it took on their children, that they swore it would never happen again. The two groups were separated. The G.o.ds bent all their will, wove the Mist as tightly as they could, to make sure the enemies never remembered each other, never met on their quests, so that bloodshed could be avoided. This map is from the final dark days of 1864, the last time the two groups fought. We've had several close calls since then. The nineteen sixties were particularly dicey. But we've managed to avoid another civil war-at least so far. Just as Leo guessed, this bunker was a command center for the Hephaestus cabin. In the last century, it has been reopened a few times, usually as a hiding place in times of great unrest. But coming here is dangerous. It stirs old memories, awakens the old feuds. Even when the t.i.tans threatened last year, I did not think it worth the risk to use this place."

Suddenly Leo's sense of triumph turned to guilt. "Hey, look, this place found me. It was meant to happen. It's a good thing."

"I hope you're right," Chiron said.

"I am!" Leo pulled the old drawing out of his pocket and spread it on the table for everyone to see.

"There," he said proudly. "Aeolus returned that to me. I drew it when I was five. That's my destiny."

Nyssa frowned. "Leo, it's a crayon drawing of a boat."

"Look." He pointed at the largest schematic on the bulletin board-the blueprint showing a Greek trireme. Slowly, his cabinmates' eyes widened as they compared the two designs. The number of masts and oars, even the decorations on the shields and sails were exactly the same as on Leo's drawing.

"That's impossible," Nyssa said. "That blueprint has to be a century old at least."

"'Prophecy-Unclear-Flight,'" Jake Mason read from the notes on the blueprint. "It's a diagram for a flying ship. Look, that's the landing gear. And weaponry-Holy Hephaestus: rotating ballista, mounted crossbows, Celestial bronze plating. That thing would be one spankin' hot war machine. Was it ever made?"

"Not yet," Leo said. "Look at the masthead."

There was no doubt-the figure at the front of the ship was the head of a dragon. A very particular dragon.

"Festus," Piper said. Everyone turned and looked at the dragon's head sitting on the table.

"He's meant to be our masthead," Leo said. "Our good luck charm, our eyes at sea. I'm supposed to build this ship.

I'm gonna call it the Argo II. And guys, I'll need your help."

"The Argo II." Piper smiled. "After Jason's ship."

Jason looked a little uncomfortable, but he nodded. "Leo's right. That ship is just what we need for our journey."

"What journey?" Nyssa said. "You just got back!"

Piper ran her fingers over the old crayon drawing. "We've got to confront Porphyrion, the giant king. He said he would destroy the G.o.ds at their roots."

"Indeed," Chiron said. "Much of Rachel's Great Prophecy is still a mystery to me, but one thing is clear. You three-Jason, Piper, and Leo-are among the seven demiG.o.ds who must take on that quest. You must confront the giants in their homeland, where they are strongest. You must stop them before they can wake Gaea fully, before they destroy Mount Olympus."

"Um ..." Nyssa shifted. "You don't mean Manhattan, do you?"

"No," Leo said. "The original Mount Olympus. We have to sail to Greece."

IT TOOK A FEW MINUTES FOR THAT TO settle in. Then the other Hephaestus campers started asking questions all at once. Who were the other four demiG.o.ds? How long would it take to build the boat? Why didn't everyone get to go to Greece?

"Heroes!" Chiron struck his hoof on the floor. "All the details are not clear yet, but Leo is correct. He will need your help to build the Argo II. It is perhaps the greatest project Cabin Nine has even undertaken, even greater than the bronze dragon."

"It'll take a year at least," Nyssa guessed. "Do we have that much time?"

"You have six months at most," Chiron said. "You should sail by summer solstice, when the G.o.ds' power is strongest. Besides, we evidently cannot trust the wind G.o.ds, and the summer winds are the least powerful and easiest to navigate. You dare not sail any later, or you may be too late to stop the giants. You must avoid ground travel, using only air and sea, so this vehicle is perfect. Jason being the son of the sky G.o.d ..."

His voice trailed off, but Leo figured Chiron was thinking about his missing student, Percy Jackson, the son of Poseidon. He would've been good on this voyage, too.

Jake Mason turned to Leo. "Well, one thing's for sure. You are now senior counselor. This is the biggest honor the cabin has ever had. Anyone object?"

n.o.body did. All his cabinmates smiled at him, and Leo could almost feel their cabin's curse breaking, their sense of hopelessness melting away.

"It's official, then," Jake said. "You're the man."

For once, Leo was speechless. Ever since his mom died, he'd spent his life on the run. Now he'd found a home and a family. He'd found a job to do. And as scary as it was, Leo wasn't tempted to run-not even a little.

"Well," he said at last, "if you guys elect me leader, you must be even crazier than I am. So let's build a spankin' hot war machine!"

JASON WAITED ALONE IN CABIN ONE.

Annabeth and Rachel were due any minute for the head counselors' meeting, and Jason needed time to think.

His dreams the night before had been worse than he'd wanted to share-even with Piper. His memory was still foggy, but bits and pieces were coming back. The night Lupa had tested him at the Wolf House, to decide if he would be a pup or food. Then the long trip south to ... he couldn't remember, but he had flashes of his old life. The day he'd gotten his tattoo. The day he'd been raised on a shield and proclaimed a praetor. His friends' faces: Dakota, Gwendolyn, Hazel, Bobby. And Reyna. Definitely there'd been a girl named Reyna. He wasn't sure what she'd meant to him, but the memory made him question what he felt about Piper-and wonder if he was doing something wrong. The problem was, he liked Piper a lot.

Jason moved his stuff to the corner alcove where his sister had once slept. He put Thalia's photograph back on the wall so he didn't feel alone. He stared up at the frowning statue of Zeus, mighty and proud, but the statue didn't scare him anymore. It just made him feel sad.

"I know you can hear me," Jason said to the statue.

The statue said nothing. Its painted eyes seemed to stare at him.

"I wish I could talk with you in person," Jason continued, "but I understand you can't do that. The Roman G.o.ds don't like to interact with mortals so much, and-well, you're the king. You've got to set an example."

More silence. Jason had hoped for something-a bigger than usual rumble of thunder, a bright light, a smile. No, never mind. A smile would've been creepy.

"I remember some things," he said. The more he talked, the less self-conscious he felt. "I remember that it's hard being a son of Jupiter. Everyone is always looking at me to be a leader, but I always feel alone. I guess you feel the same way up on Olympus. The other G.o.ds challenge your decisions. Sometimes you've got to make hard choices, and the others criticize you. And you can't come to my aid like other G.o.ds might. You've got to keep me at a distance so it doesn't look like you're playing favorites. I guess I just wanted to say ..."

Jason took a deep breath. "I understand all that. It's okay. I'm going to try to do my best. I'll try to make you proud. But I could really use some guidance, Dad. If there's anything you can do-help me so I can help my friends. I'm afraid I'll get them killed. I don't know how to protect them."

The back of his neck tingled. He realized someone was standing behind him. He turned and found a woman in a black hooded robe, with a goatskin cloak over her shoulders and a sheathed Roman sword-a gladius-in her hands.

"Hera," he said.

She pushed back her hood. "To you, I have always been Juno. And your father has already sent you guidance, Jason. He sent you Piper and Leo. They're not just your responsibility. They are also your friends. Listen to them, and you will do well."

"Did Jupiter send you here to tell me that?"

"No one sends me anywhere, hero," she said. "I am not a messenger."

"But you got me into this. Why did you send me to this camp?"

"I think you know," Juno said. "An exchange of leaders was necessary. It was the only way to bridge to gap."

"I didn't agree to it."

"No. But Zeus gave your life to me, and I am helping you fulfill your destiny."

Jason tried to control his anger. He looked down at his orange camp shirt and the tattoos on his arm, and he knew these things should not go together. He had become a contradiction-a mixture as dangerous as anything Medea could cook up.

"You're not giving me all my memories," he said. "Even though you promised."

"Most will return in time," Juno said. "But you must find your own way back. You need these next months with your new friends, your new home. You're gaining their trust. By the time you sail in your ship, you will be a leader at this camp. And you will be ready to be a peacemaker between two great powers."

"What if you're not telling the truth?" he asked. "What if you're doing this to cause another civil war?"

Juno's expression was impossible to read-amus.e.m.e.nt? Disdain? Affection? Possibly all three. As much as she appeared human, Jason knew she was not. He could still see that blinding light-the true form of the G.o.ddess that had seared itself into his brain. She was Juno and Hera. She existed in many places at once. Her reasons for doing something were never simple.

"I am the G.o.ddess of family," she said. "My family has been divided for too long."

"They divided us so we don't kill each other," Jason said. "That seems like a pretty good reason."

"The prophecy demands that we change. The giants will rise. Each can only be killed by a G.o.d and demiG.o.d working together. Those demiG.o.ds must be the seven greatest of the age. As it stands, they are divided between two places. If we remain divided, we cannot win. Gaea is counting on this. You must unite the heroes of Olympus and sail together to meet the giants on the ancient battlegrounds of Greece. Only then will the G.o.ds be convinced to join you. It will be the most dangerous quest, the most important voyage, ever attempted by the children of the G.o.ds."

Jason looked up again at the glowering statue of his father.

"It's not fair," Jason said. "I could ruin everything."

"You could," Juno agreed. "But G.o.ds need heroes. We always have."

"Even you? I thought you hated heroes."

The G.o.ddess gave him a dry smile. "I have that reputation. But if you want the truth, Jason, I often envy other G.o.ds their mortal children. You demiG.o.ds can span both worlds. I think this helps your G.o.dly parents-even Jupiter, curse him-to understand the mortal world better than I."

Juno sighed so unhappily that despite his anger, Jason almost felt sorry for her.

"I am the G.o.ddess of marriage," she said. "It is not in my nature to be faithless. I have only two G.o.dly children-Ares and Hephaestus-both of whom are disappointments. I have no mortal heroes to do my bidding, which is why I am so often bitter toward demiG.o.ds-Heracles, Aeneas, all of them. But it is also why I favored the first Jason, a pure mortal, who had no G.o.dly parent to guide him. And why I am glad Zeus gave you to me. You will be my champion, Jason. You will be the greatest of heroes, and bring unity to the demiG.o.ds, and thus to Olympus."

Her words settled over him, as heavy as sandbags. Two days ago, he'd been terrified by the idea of leading demiG.o.ds into a Great Prophecy, sailing off to battle the giants and save the world.

He was still terrified, but something had changed. He no longer felt alone. He had friends now, and a home to fight for. He even had a patron G.o.ddess looking out for him, which had to count for something, even if she seemed a little untrustworthy.