At last he said, "It is not Kronos. That threat is ended. But ..."

"But what?" Annabeth asked.

Chiron closed the medicine bag. "Piper needs rest. We should discuss this later."

"Or now," Jason said. "Sir, Mr. Chiron, you told me the greatest threat was coming. The last chapter. You can't possibly mean something worse than an army of t.i.tans, right?"

"Oh," Rachel said in a small voice. "Oh, dear. The woman was Hera. Of course. Her cabin, her voice. She showed herself to Jason at the same moment."

"Hera?" Annabeth's snarl was even fiercer than Seymour's. "She took you over? She did this to Piper?"

"I think Rachel's right," Jason said. "The woman did seem like a G.o.ddess. And she wore this-this goatskin cloak. That's a symbol of Juno, isn't it?"

"It is?" Annabeth scowled. "I've never heard that."

Chiron nodded reluctantly. "Of Juno, Hera's Roman aspect, in her most warlike state. The goatskin cloak was a symbol of the Roman soldier."

"So Hera is imprisoned?" Rachel asked. "Who could do that to the queen of the G.o.ds?"

Annabeth crossed her arms. "Well, whoever they are, maybe we should thank them. If they can shut up Hera-"

"Annabeth," Chiron warned, "she is still one of the Olympians. In many ways, she is the glue that holds the G.o.ds' family together. If she truly has been imprisoned and is in danger of destruction, this could shake the foundations of the world. It could unravel the stability of Olympus, which is never great even in the best of times. And if Hera has asked Jason for help-"

"Fine," Annabeth grumbled. "Well, we know t.i.tans can capture a G.o.d, right? Atlas captured Artemis a few years ago. And in the old stories, the G.o.ds captured each other in traps all the time. But something worse than a t.i.tan ... ?"

Jason looked at the leopard's head. Seymour was smacking his lips like the G.o.ddess had tasted much better than a Snausage. "Hera said she'd been trying to break through her prison bonds for a month."

"Which is how long Olympus has been closed," Annabeth said. "So the G.o.ds must know something bad is going on."

"But why use her energy to send me here?" Jason asked. "She wiped my memory, plopped me into the Wilderness School field trip, and sent you a dream vision to come pick me up. Why am I so important? Why not just send up an emergency flare to the other G.o.ds-let them know where she is so they bust her out?"

"The G.o.ds need heroes to do their will down here on earth," Rachel said. "That's right, isn't it? Their fates are always intertwined with demiG.o.ds."

"That's true," Annabeth said, "but Jason's got a point. Why him? Why take his memory?"

"And Piper's involved somehow," Rachel said. "Hera sent her the same message-Free me. And, Annabeth, this must have something to do with Percy's disappearing."

Annabeth fixed her eyes on Chiron. "Why are you so quiet, Chiron? What is it we're facing?"

The old centaur's face looked like it had aged ten years in a matter of minutes. The lines around his eyes were deeply etched. "My dear, in this, I cannot help you. I am so sorry."

Annabeth blinked. "You've never ... you've never kept information from me. Even the last great prophecy-"

"I will be in my office." His voice was heavy. "I need some time to think before dinner. Rachel, will you watch the girl? Call Argus to bring her to the infirmary, if you'd like. And Annabeth, you should speak with Jason. Tell him about-about the Greek and Roman G.o.ds."

"But ..."

The centaur turned his wheelchair and rolled off down the hallway. Annabeth's eyes turned stormy. She muttered something in Greek, and Jason got the feeling it wasn't complimentary toward centaurs.

"I'm sorry," Jason said. "I think my being here-I don't know. I've messed things up coming to the camp, somehow. Chiron said he'd sworn an oath and couldn't talk about it."

"What oath?" Annabeth demanded. "I've never seen him act this way. And why would he tell me to talk to you about the G.o.ds..."

Her voice trailed off. Apparently she'd just noticed Jason's sword sitting on the coffee table. She touched the blade gingerly, like it might be hot.

"Is this gold?" she said. "Do you remember where you got it?"

"No," Jason said. "Like I said, I don't remember anything."

Annabeth nodded, like she'd just come up with a rather desperate plan. "If Chiron won't help, we'll need to figure things out ourselves. Which means ... Cabin Fifteen. Rachel, you'll keep an eye on Piper?"

"Sure," Rachel promised. "Good luck, you two."

"Hold on," Jason said. "What's in Cabin Fifteen?"

Annabeth stood. "Maybe a way to get your memory back."

They headed toward a newer wing of cabins in the southwest corner of the green. Some were fancy, with glowing walls or blazing torches, but Cabin Fifteen was not so dramatic. It looked like an old-fashioned prairie house with mud walls and a rush roof. On the door hung a wreath of crimson flowers-red poppies, Jason thought, though he wasn't sure how he knew.

"You think this is my parent's cabin?" he asked.

"No," Annabeth said. "This is the cabin for Hypnos, the G.o.d of sleep."

"Then why-"

"You've forgotten everything," she said. "If there's any G.o.d who can help us figure out memory loss, it's Hypnos."

Inside, even though it was almost dinnertime, three kids were sound asleep under piles of covers. A warm fire crackled in the hearth. Above the mantel hung a tree branch, each twig dripping white liquid into a collection of tin bowls. Jason was tempted to catch a drop on his finger just to see what it was, but he held himself back.

Soft violin music played from somewhere. The air smelled like fresh laundry. The cabin was so cozy and peaceful that Jason's eyelids started to feel heavy. A nap sounded like a great idea. He was exhausted. There were plenty of empty beds, all with feather pillows and fresh sheets and fluffy quilts and-Annabeth nudged him. "Snap out of it."

Jason blinked. He realized his knees had been starting to buckle.

"Cabin Fifteen does that to everyone," Annabeth warned. "If you ask me, this place is even more dangerous than the Ares cabin. At least with Ares, you can learn where the land mines are."

"Land mines?"

She walked up to the nearest snoring kid and shook his shoulder. "Clovis! Wake up!"

The kid looked like a baby cow. He had a blond tuft of hair on a wedge-shaped head, with thick features and a thick neck. His body was stocky, but he had spindly little arms like he'd never lifted anything heavier than a pillow.

"Clovis!" Annabeth shook harder, then finally knocked on his forehead about six times.

"Wh-wh-what?" Clovis complained, sitting up and squinting. He yawned hugely, and both Annabeth and Jason yawned too.

"Stop that!" Annabeth said. "We need your help."

"I was sleeping."

"You're always sleeping."

"Good night."

Before he could pa.s.s out, Annabeth yanked his pillow offthe bed.

"That's not fair," Clovis complained meekly. "Give it back."

"First help," Annabeth said. "Then sleep."

Clovis sighed. His breath smelled like warm milk. "Fine. What?"

Annabeth explained about Jason's problem. Every once in a while she'd snap her fingers under Clovis's nose to keep him awake.

Clovis must have been really excited, because when Annabeth was done, he didn't pa.s.s out. He actually stood and stretched, then blinked at Jason. "So you don't remember anything, huh?"

"Just impressions," Jason said. "Feelings, like ..."

"Yes?" Clovis said.

"Like I know I shouldn't be here. At this camp. I'm in danger."

"Hmm. Close your eyes."

Jason glanced at Annabeth, but she nodded rea.s.suringly.

Jason was afraid he'd end up snoring in one of the bunks forever, but he closed his eyes. His thoughts became murky, as if he were sinking into a dark lake.

The next thing he knew, his eyes snapped open. He was sitting in a chair by the fire. Clovis and Annabeth knelt next to him.

"-serious, all right," Clovis was saying.

"What happened?" Jason said. "How long-"

"Just a few minutes," Annabeth said. "But it was tense. You almost dissolved."

Jason hoped she didn't mean literally, but her expression was solemn.

"Usually," Clovis said, "memories are lost for a good reason. They sink under the surface like dreams, and with a good sleep, I can bring them back. But this ..."

"Lethe?" Annabeth asked.

"No," Clovis said. "Not even Lethe."

"Lethe?" Jason asked.

Clovis pointed to the tree branch dripping milky drops above the fireplace. "The River Lethe in the Underworld. It dissolves your memories, wipes your mind clean permanently. That's the branch of a poplar tree from the Underworld, dipped into the Lethe. It's the symbol of my father, Hypnos. Lethe is not a place you want to go swimming."

Annabeth nodded. "Percy went there once. He told me it was powerful enough to wipe the mind of a t.i.tan."

Jason was suddenly glad he hadn't touched the branch. "But ... that's not my problem?"

"No," Clovis agreed. "Your mind wasn't wiped, and your memories weren't buried. They've been stolen."

The fire crackled. Drops of Lethe water plinked into the tin cups on the mantel. One of the other Hypnos campers muttered in his sleep-something about a duck.

"Stolen," Jason said. "How?"

"A G.o.d," Clovis said. "Only a G.o.d would have that kind of power."

"We know that," said Jason. "It was Juno. But how did she do it, and why?"

Clovis scratched his neck. "Juno?"

"He means Hera," Annabeth said. "For some reason, Jason likes the Roman names."

"Hmm," Clovis said.

"What?" Jason asked. "Does that mean something?"

"Hmm," Clovis said again, and this time Jason realized he was snoring.

"Clovis!" he yelled.

"What? What?" His eyes fluttered open. "We were talking about pillows, right? No, G.o.ds. I remember. Greek and Roman. Sure, could be important."

"But they're the same G.o.ds," Annabeth said. "Just different names."

"Not exactly," Clovis said.

Jason sat forward, now very much awake. "What do you mean, not exactly?"

"Well ..." Clovis yawned. "Some G.o.ds are only Roman. Like Ja.n.u.s, or Pompona. But even the major Greek G.o.ds-it's not just their names that changed when they moved to Rome. Their appearances changed. Their attributes changed. They even had slightly different personalities."

"But ..." Annabeth faltered. "Okay, so maybe people saw them differently through the centuries. That doesn't change who they are."

"Sure it does." Clovis began to nod off, and Jason snapped his fingers under his nose.

"Coming, Mother!" he yelped. "I mean ... Yeah, I'm awake. So, um, personalities. The G.o.ds change to reflect their host cultures. You know that, Annabeth. I mean, these days, Zeus likes tailored suits, reality television, and that Chinese food place on East Twenty-eighth Street, right? It was the same in Roman times, and the G.o.ds were Roman almost as long as they were Greek. It was a big empire, lasted for centuries. So of course their Roman aspects are still a big part of their character."

"Makes sense," Jason said.

Annabeth shook her head, mystified. "But how do you know all this, Clovis?"

"Oh, I spend a lot of time dreaming. I see the G.o.ds there all the time-always shifting forms. Dreams are fluid, you know. You can be in different places at once, always changing ident.i.ties. It's a lot like being a G.o.d, actually. Like recently, I dreamed I was watching a Michael Jackson concert, and then I was onstage with Michael Jackson, and we were singing this duet, and I could not remember the words for 'The Girl Is Mine.' Oh, man, it was so embarra.s.sing, I-"

"Clovis," Annabeth interrupted. "Back to Rome?"

"Right, Rome," Clovis said. "So we call the G.o.ds by their Greek names because that's their original form. But saying their Roman aspects are exactly the same-that's not true. In Rome, they became more warlike. They didn't mingle with mortals as much. They were harsher, more powerful-the G.o.ds of an empire."