"No!" Piper yelled.

All around her, the fields crackled and hissed, laughing in Gaea's voice as Percy and Jason charged at each other, their weapons ready.

If not for the horses, Piper would've died.

Jason and Percy charged each other, but Tempest and Blackjack balked long enough for Piper to leap out of the way.

She rolled to the edge of the road and looked back, dazed and horrified, as the boys crossed swords, gold against bronze. Sparks flew. Their blades blurred-strike and parry-and the pavement trembled. The first exchange took only a second, but Piper couldn't believe the speed of their sword fighting. The horses pulled away from each other-Tempest thundering in protest, Blackjack flapping his wings.

"Stop it!" Piper yelled.

For a moment, Jason heeded her voice. His golden eyes turned toward her, and Percy charged, slamming his blade into Jason. Thank the gods, Percy turned his sword-maybe on purpose, maybe accidentally-so the flat of it hit Jason's chest; but the impact was still enough to knock Jason off his mount.

Blackjack cantered away as Tempest reared in confusion. The spirit horse charged into the sunflowers and dissipated into vapor.

Percy struggled to turn his pegasus around.

"Percy!" Piper yelled. "Jason's your friend. Drop your weapon!"

Percy's sword arm dipped. Piper might have been able to bring him under control, but unfortunately Jason got to his feet.

Jason roared. A bolt of lightning arced out of the clear blue sky. It ricocheted off his gladius and blasted Percy off his horse.

Blackjack whinnied and fled into the wheat fields. Jason charged at Percy, who was now on his back, his clothes smoking from the lightning blast.

For a horrible moment, Piper couldn't find her voice. Gaea seemed to be whispering to her: You must choose one. Why not let Jason kill him?

"No!" she screamed. "Jason, stop!"

He froze, his sword six inches from Percy's face.

Jason turned, the gold light in his eyes flickering uncertainly. "I cannot stop. One must die."

Something about that voice...it wasn't Gaea. It wasn't Jason. Whoever it was spoke haltingly, as if English was its second language.

"Who are you?" Piper demanded.

Jason's mouth twisted in a gruesome smile. "We are the eidolons. We will live again."

"Eidolons... ?" Piper's mind raced. She'd studied all sorts of monsters at Camp Half-Blood, but that term wasn't familiar. "You're-you're some sort of ghost?"

"He must die." Jason turned his attention back to Percy, but Percy had recovered more than either of them realized. He swept out his leg and knocked Jason off his feet.

Jason's head hit the asphalt with a nauseating conk.

Percy rose.

"Stop it!" Piper screamed again, but there was no charmspeak in her voice. She was shouting in sheer desperation.

Percy raised Riptide over Jason's chest.

Panic closed up Piper's throat. She wanted to attack Percy with her dagger, but she knew that wouldn't help. Whatever was controlling him had all of Percy's skill. There was no way she could beat him in combat.

She forced herself to focus. She poured all of her anger into her voice. "Eidolon, stop."

Percy froze.

"Face me," Piper ordered.

The son of the sea god turned. His eyes were gold instead of green, his face pale and cruel, not at all like Percy's.

"You have not chosen," he said. "So this one will die."

"You're a spirit from the Underworld," Piper guessed. "You're possessing Percy Jackson. Is that it?"

Percy sneered. "I will live again in this body. The Earth Mother has promised. I will go where I please, control whom I wish."

A wave of cold washed over Piper. "Leo...that's what happened to Leo. He was being controlled by an eidolon."

The thing in Percy's form laughed without humor. "Too late you realize. You can trust no one."

Jason still wasn't moving. Piper had no help, no way to protect him.

Behind Percy, something rustled in the wheat. Piper saw the tip of a black wing, and Percy began to turn toward the sound.

"Ignore it!" she yelped. "Look at me."

Percy obeyed. "You cannot stop me. I will kill Jason Grace."

Behind him, Blackjack emerged from the wheat field, moving with surprising stealth for such a large animal.

"You won't kill him," Piper ordered. But she wasn't looking at Percy. She locked eyes with the pegasus, pouring all her power into her words and hoping Blackjack would understand. "You will knock him out."

The charmspeak washed over Percy. He shifted his weight indecisively. "I...will knock him out?"

"Oh, sorry." Piper smiled. "I wasn't talking to you."

Blackjack reared and brought his hoof down on Percy's head.

Percy crumpled to the pavement next to Jason.

"Oh, gods!" Piper ran to the boys. "Blackjack, you didn't kill him, did you?"

The pegasus snorted. Piper couldn't speak Horse, but she thought he might have said: Please. I know my own strength.

Tempest was nowhere to be seen. The lightning steed had apparently returned to wherever storm spirits live on clear days.

Piper checked on Jason. He was breathing steadily, but two knocks on the skull in two days couldn't have been good for him. Then she examined Percy's head. She didn't see any blood, but a large knot was forming where the horse had kicked him. "We have to get them both back to the ship," she told Blackjack.

The pegasus bobbed his head in agreement. He knelt to the ground, so that Piper could drape Percy and Jason over his back. After a lot of hard work (unconscious boys were heavy), she got them reasonably secured, climbed onto Blackjack's back herself, and they took off for the ship.

The others were a little surprised when Piper came back on a pegasus with two unconscious demigods. While Frank and Hazel tended to Blackjack, Annabeth and Leo helped get Piper and the boys to the sickbay.

"At this rate, we're going to run out of ambrosia," Coach Hedge grumbled as he tended their wounds. "How come I never get invited on these violent trips?"

Piper sat at Jason's side. She herself felt fine after a swig of nectar and some water, but she was still worried about the boys.

"Leo," Piper said, "are we ready to sail?"

"Yeah, but-"

"Set course for Atlanta. I'll explain later."

"But...okay." He hurried off.

Annabeth didn't argue with Piper either. She was too busy examining the horseshoe-shaped dent on the back of Percy's head.

"What hit him?" she demanded.

"Blackjack," Piper said.

"What?"

Piper tried to explain while Coach Hedge applied some healing paste to the boys' heads. She'd never been impressed with Hedge's nursing abilities before, but he must have done something right. Either that, or the spirits that possessed the boys had also made them extra resilient. They both groaned and opened their eyes.

Within a few minutes, Jason and Percy were sitting up in their berths and able to talk in complete sentences. Both had fuzzy memories of what had happened. When Piper described their duel on the highway, Jason winced.

"Knocked out twice in two days," he muttered. "Some demigod." He glanced sheepishly at Percy. "Sorry, man. I didn't mean to blast you."

Percy's shirt was peppered with burn holes. His hair was even more disheveled than normal. Despite that, he managed a weak laugh. "Not the first time. Your big sister got me good once at camp."

"Yeah, but...I could have killed you."

"Or I could have killed you," Percy said.

Jason shrugged. "If there'd been an ocean in Kansas, maybe."

"I don't need an ocean-"

"Boys," Annabeth interrupted, "I'm sure you both would've been wonderful at killing each other. But right now, you need some rest."

"Food first," Percy said. "Please? And we really need to talk. Bacchus said some things that don't-"

"Bacchus?" Annabeth raised her hand. "Okay, fine. We need to talk. Mess hall. Ten minutes. I'll tell the others. And please, Percy...change your clothes. You smell like you've been run over by an electric horse."

Leo gave the helm to Coach Hedge again, after making the satyr promise he would not steer them to the nearest military base "for fun."

They gathered around the dining table, and Piper explained what had happened at TOPEKA 32-their conversation with Bacchus, the trap sprung by Gaea, the eidolons that had possessed the boys.

"Of course!" Hazel slapped the table, which startled Frank so much, he dropped his burrito. "That's what happened to Leo too."

"So it wasn't my fault." Leo exhaled. "I didn't start World War Three. I just got possessed by an evil spirit. That's a relief!"

"But the Romans don't know that," Annabeth said. "And why would they take our word for it?"

"We could contact Reyna," Jason suggested. "She would believe us."

Hearing the way Jason said her name, like it was a lifeline to his past, made Piper's heart sink.

Jason turned to her with a hopeful gleam in his eyes. "You could convince her, Pipes. I know you could."

Piper felt like all the blood in her body was draining into her feet. Annabeth looked at her sympathetically, as if to say: Boys are so clueless. Even Hazel winced.

"I could try," she said halfheartedly. "But Octavian is the one we have to worry about. In my dagger blade, I saw him taking control of the Roman crowd. I'm not sure Reyna can stop him."

Jason's expression darkened. Piper didn't get any pleasure from bursting his bubble, but the other Romans-Hazel and Frank-nodded in agreement.

"She's right," Frank said. "This afternoon when we were scouting, we saw eagles again. They were a long way off, but closing fast. Octavian is on the warpath."

Hazel grimaced. "This is exactly the sort of opportunity Octavian has always wanted. He'll try to seize power. If Reyna objects, he'll say she's soft on the Greeks. As for those eagles...It's like they could smell us."

"They can," Jason said. "Roman eagles can hunt demigods by their magical scent even better than monsters can. This ship might conceal us somewhat, but not completely-not from them."

Leo drummed his fingers. "Great. I should have installed a smoke screen that makes the ship smell like a giant chicken nugget. Remind me to invent that, next time."

Hazel frowned. "What is a chicken nugget?"

"Oh, man..." Leo shook his head in amazement. "That's right. You've missed the last like, seventy years. Well, my apprentice, a chicken nugget-"

"Doesn't matter," Annabeth interrupted. "The point is, we'll have a hard time explaining the truth to the Romans. Even if they believe us-"

"You're right." Jason leaned forward. "We should just keep going. Once we're over the Atlantic, we'll be safe-at least from the legion."

He sounded so depressed, Piper didn't know whether to feel sorry for him or resentful. "How can you be sure?" she asked. "Why wouldn't they follow us?"

He shook his head. "You heard Reyna talking about the ancient lands. They're much too dangerous. Roman demigods have been forbidden to go there for generations. Even Octavian couldn't get around that rule."

Frank swallowed a bite of burrito like it had turned to cardboard in his mouth. "So, if we go there..."

"We'll be outlaws as well as traitors," Jason confirmed. "Any Roman demigod would have the right to kill us on sight. But I wouldn't worry about that. If we get across the Atlantic, they'll give up on chasing us. They'll assume that we'll die in the Mediterranean-the Mare Nostrum."

Percy pointed his pizza slice at Jason. "You, sir, are a ray of sunshine."

Jason didn't argue. The other demigods stared at their plates, except for Percy, who continued to enjoy his pizza. Where he put all that food, Piper didn't know. The guy could eat like a satyr.

"So let's plan ahead," Percy suggested, "and make sure we don't die. Mr. D-Bacchus- Ugh, do I have to call him Mr. B now? Anyway, he mentioned the twins in Ella's prophecy. Two giants. Otis and, uh, something that started with an F?"

"Ephialtes," Jason said.