Outside Camp Jupiter, California

They reached the riverbank, and Percy Jackson stopped to catch his breath. The current was fast, but the river didn't look deep. Only a stone's throw across stood the gates of the fort.

"Go, Hazel." Frank Zhang nocked two arrows at once. "Escort Percy so the sentries don't shoot him. It's my turn to hold off the baddies."

Hazel Levesque nodded and waded into the stream.

Percy started to follow, but something made him hesitate. Usually, he loved the water, but this river seemed . . . powerful, and not necessarily friendly.

"The Little Tiber," said June sympathetically. "It flows with the power of the original Tiber river of the empire. This is your last chance to back out, child. The mark of Achilles is a Greek blessing. You can't retain it if you cross into Roman territory. The Tiber will wash it away."

Percy was too exhausted to understand all that, but he got the main point. "If I cross, I won't have iron skin anymore?"

June smiled. "So what will it be? Safety, or a future of pain and possibility?"

Behind him, the gorgons screeched as they flew from the tunnel. Frank let his arrows fly.

From the middle of the river, Hazel yelled, "Percy, come on!"

Up on the watchtowers, horns blew. The sentries shouted and swiveled their crossbows toward the gorgons.

Percy tightened his grip around June. Whoever this lady was, he didn't entirely trust her. She might be right about the Tiber, but she didn't know Percy. He didn't really know himself, either, but he was sure of one thing—he wasn't ready to give up the mark of Achilles. If it was Greek, maybe that had something to do with his past. With Annabeth. Percy wasn't willing to let that go.

He operated on instinct. He felt a tug in his gut as he took the first step into the river, and his thoughts became reality. The river parted around his feet, leaving him and June untouched by the water.

"Interesting choice," the old lady murmured, almost disapproving. Percy didn't care.

He could have used the energy boost that he had discovered in the last few days that water gave him, but he could last a little bit longer if it meant retaining a connection to his past. June seemed to have tripled in weight, and the thought of finally putting her down once they crossed the river drove him forward.

He could sense that he'd succeeded once he reached the other side and put the old woman down. The atmosphere here . . . it didn't like him, or his Greek blessing. But Percy had kept it for now, and that was all that mattered.

The camp's gates opened. Dozens of kids in armor poured out.

Hazel turned with a relieved smile. Then she looked over Percy's shoulder, and her expression changed to horror. "Frank!"

Frank was halfway across the river when the gorgons caught him. They swooped out of the sky and grabbed him by either arm. He screamed in pain as their claws dug into his skin.

The sentries yelled, but Percy knew they couldn't get a clear shot. They'd end up killing Frank. The other kids drew swords and got ready to charge into the water, but they'd be too late.

There was only one way.

Percy thrust out his hands. An intense tugging sensation filled his gut, and the Tiber obeyed his will. The river surged. Whirlpools formed on either side of Frank. Giant watery hands erupted from the stream, copying Percy's movements. The giant hands grabbed the gorgons, who dropped Frank in surprise. Then the hands lifted the squawking monsters in a liquid vise grip.

Percy heard the other kids yelping and backing away, but he stayed focused on his task. He made a smashing gesture with his fists, and the giant hands plunged the gorgons into the Tiber. The monsters hit bottom and broke into dust. Glittering clouds of gorgon essence struggled to re-form, but the river pulled them apart like a blender. Soon, every trace of the gorgons was swept downstream. The whirlpools vanished, and the current returned to normal.

In the middle of the Tiber, Frank stumbled around, looking stunned but perfectly fine. Hazel waded out and helped him ashore. Only then did Percy realize how quiet the other kids had become.

Everyone was staring at him. Only the old lady June looked unfazed.

"Well, that was a lovely trip," she said. "Thank you, Percy Jackson, for bringing me to Camp Jupiter."

One of the girls made a choking sound. "Percy . . . Jackson?"

She sounded as if she recognized his name. Percy focused on her, hoping to see a familiar face.

She was obviously a leader. She wore a regal purple cloak over her armor. Her chest was decorated with medals. She must have been about Percy's age, with dark, piercing eyes and long black hair. Percy didn't recognize her, but the girl stared at him as if she'd seen him in her nightmares.

June laughed with delight. "Oh, yes. You'll have such fun together!"

Then, just because the day hadn't been weird enough already, the old lady began to glow and change form. She grew until she was a shining, seven-foot-tall goddess in a blue dress, with a cloak that looked like goat's skin over her shoulders. Her face was stern and stately. In her hand was a staff topped with a lotus flower.

If it was possible for the campers to look more stunned, they did. The girl with the purple cloak knelt. The others followed her lead. One kid got down so hastily he almost impaled himself on his sword.

Hazel was the first to speak. "Juno."

She and Frank also fell to their knees, leaving Percy the only one standing. He knew he should probably kneel too, but after carrying the old lady so far, he didn't feel like showing her that much respect.

"Juno, huh?" he said. "If I passed your test, can I have my memory and my life back?"

The goddess smiled. "In time, Percy Jackson, if you succeed here at camp. You've done well today, which is a good start. Perhaps there's hope for you yet."

She turned to the other kids. "Romans, I present to you the son of Neptune. For months he has been slumbering, but now he is awake. His fate is in your hands. The Feast of Fortune comes quickly, and Death must be unleashed if you are to stand any hope in the battle. Do not fail me!"

Juno shimmered and disappeared. Percy looked at Hazel and Frank for some kind of explanation, but they seemed just as confused as he was. Frank was holding something Percy hadn't noticed before—two small clay flasks with cork stoppers, like potions, one in each hand. Percy had no idea where they'd come from, but he saw Frank slip them into his pockets. Frank gave him a look like: We'll talk about it later.

The girl in the purple cloak stepped forward. She examined Percy warily, and Percy couldn't shake the feeling that she wanted to run him through with her dagger.

"So," she said coldly, "a son of Neptune, who comes to us with the blessing of Juno."

"Look," he said, "my memory's a little fuzzy. Um, it's gone, actually. Do I know you?"

The girl hesitated. "I am Reyna, praetor of the Twelfth Legion. And . . . no, I don't know you."

That last part was a lie. Percy could tell from her eyes. But he also understood that if he argued with her about it here, in front of her soldiers, she wouldn't appreciate it.

"Hazel," said Reyna, "bring him inside. I want to question him at the principia. Then we'll send him to Octavian. We must consult the auguries before we decide what to do with him."

"What do you mean," Percy asked, "'decide what to do with' me?"

Reyna's hand tightened on her dagger. Obviously, she was not used to having her orders questioned. "Before we accept anyone into camp, we must interrogate them and read the auguries. Juno said your fate is in our hands. We have to know whether the goddess has brought us a new recruit . . ."

Reyna studied Percy as if she found that doubtful.

"Or," she said more hopefully, "if she's brought us an enemy to kill."

She spun on her heel and stalked away. Hazel stepped forward to lead Percy into the camp. He took one last look at the Tiber and made a silent vow not to tell anyone about the mark of Achilles. Maybe they'd be able to help him sort out his past, but for now, that was one secret he'd keep to himself—that, and Annabeth.