he next few days I settled into a routine that felt almost normal, if you don't count the fact that I was getting lessons from satyrs, nymphs, and a centaur.

Each morning I took Ancient Greek from Annabeth, and we talked about the gods and goddesses in the present tense, which was kind of weird. I discovered Annabeth was right about my dyslexia: Ancient Greek wasn't that hard for me to read. At least, no harder than English. After a couple of mornings, I could stumble through a few lines of Homer without too much headache.

The rest of the day, I'd rotate through outdoor activities, looking for something I was good at. Chiron tried to teach me archery, but we found out pretty quick I wasn't any good with a bow and arrow. He didn't complain, even when he had to desnag a stray arrow out of his tail.

Foot racing? No good either. The wood-nymph instructors left me in the dust. They told me not to worry about it. They'd had centuries of practice running away from lovesick gods. But still, it was a little humiliating to be slower than a tree.

And wrestling? Forget it. Every time I got on the mat, Clarisse would pulverize me.

"There's more where that came from, punk," she'd mumble in my ear.

The only thing I really excelled at was canoeing, and that wasn't the kind of heroic skill people expected to see from the kid who had beaten the Minotaur.

I knew the senior campers and counselors were watching me, trying to decide who my dad was, but they weren't having an easy time of it. I wasn't as strong as the Ares kids, or as good at archery as the Apollo kids. I didn't have Hephaestus's skill with metalwork or—gods forbid— Dionysus's way with vine plants. Luke told me I might be a child of Hermes, a kind of jack-of-all-trades, master of none. But I got the feeling he was just trying to make me feel better. He really didn't know what to make of me either.

Despite all that, I liked camp. I got used to the morning fog over the beach, the smell of hot strawberry fields in the afternoon, even the weird noises of monsters in the woods at night. I would eat dinner with cabin eleven, scrape part of my meal into the fire, and try to feel some connection to my real dad. Nothing came. Just that warm feeling I'd always had, like the memory of his smile. I tried not to think too much about my mom, but I kept wondering: if gods and monsters were real, if all this magical stuff was possible, surely there was some way to save her, to bring her back....

I started to understand Luke's bitterness and how he seemed to resent his father, Hermes. So okay, maybe gods had important things to do. But couldn't they call once in a while, or thunder, or something? Dionysus could make Diet Coke appear out of thin air. Why couldn't my dad, whoever he was, make a phone appear?

Thursday afternoon, three days after I'd arrived at CampHalf-Blood, I had my first sword-fighting lesson. Everybody from cabin eleven gathered in the big circular arena, where Luke would be our instructor.

We started with basic stabbing and slashing, using some straw-stuffed dummies in Greek armor. I guess I did okay. At least, I understood what I was supposed to do and my reflexes were good.

The problem was, I couldn't find a blade that felt right in my hands. Either they were too heavy, or too light, or too long. Luke tried his best to fix me up, but he agreed that none of the practice blades seemed to work for me.

We moved on to dueling in pairs. Luke announced he would be my partner, since this was my first time.

"Good luck," one of the campers told me. "Luke's the best swordsman in the last three hundred years."

"Maybe he'll go easy on me," I said.

The camper snorted.

Luke showed me thrusts and parries and shield blocks the hard way. With every swipe, I got a little more battered and bruised. "Keep your guard up, Percy," he'd say, then whap me in the ribs with the flat of his blade. "No, not that far up!" Whap! "Lunge!" Whap! "Now, back!" Whap!

By the time he called a break, I was soaked in sweat. Everybody swarmed the drinks cooler. Luke poured ice water on his head, which looked like such a good idea, I did the same.

Instantly, I felt better. Strength surged back into my arms. The sword didn't feel so awkward.

"Okay, everybody circle up!" Luke ordered. "If Percy doesn't mind, I want to give you a little demo."

Great, I thought. Let's all watch Percy get pounded.

The Hermes guys gathered around. They were suppressing smiles. I figured they'd been in my shoes before and couldn't wait to see how Luke used me for a punching bag. He told everybody he was going to demonstrate a disarming technique: how to twist the enemy's blade with the flat of your own sword so that he had no choice but to drop his weapon.

"This is difficult," he stressed. "I've had it used against me. No laughing at Percy, now. Most swordsmen have to work years to master this technique."

He demonstrated the move on me in slow motion. Sure enough, the sword clattered out of my hand.

"Now in real time," he said, after I'd retrieved my weapon. "We keep sparring until one of us pulls it off. Ready, Percy?"

I nodded, and Luke came after me. Somehow, I kept him from getting a shot at the hilt of my sword. My senses opened up. I saw his attacks coming. I countered. I stepped forward and tried a thrust of my own. Luke deflected it easily, but I saw a change in his face. His eyes narrowed, and he started to press me with more force.

The sword grew heavy in my hand. The balance wasn't right. I knew it was only a matter of seconds before Luke took me down, so I figured, What the heck?

I tried the disarming maneuver.

My blade hit the base of Luke's and I twisted, putting my whole weight into a downward thrust.

Clang.

Luke's sword rattled against the stones. The tip of my blade was an inch from his undefended chest.

The other campers were silent.

I lowered my sword. "Um, sorry."

For a moment, Luke was too stunned to speak.

"Sorry?" His scarred face broke into a grin. "By the gods, Percy, why are you sorry? Show me that again!"

I didn't want to. The short burst of manic energy had completely abandoned me. But Luke insisted.

This time, there was no contest. The moment our swords connected, Luke hit my hilt and sent my weapon skidding across the floor.

After a long pause, somebody in the audience said, "Beginner's luck?"

Luke wiped the sweat off his brow. He appraised at me with an entirely new interest. "Maybe," he said. "But I wonder what Percy could do with a balanced sword...."

Friday afternoon, I was sitting with Grover at the lake, resting from a near-death experience on the climbing wall. Grover had scampered to the top like a mountain goat, but the lava had almost gotten me. My shirt had smoking holes in it. The hairs had been singed off my forearms.

We sat on the pier, watching the naiads do underwater basket-weaving, until I got up the nerve to ask Grover how his conversation had gone with Mr. D.

His face turned a sickly shade of yellow.

"Fine," he said. "Just great."

"So your career's still on track?"

He glanced at me nervously. "Chiron t-told you I want a searcher's license?"

"Well... no." I had no idea what a searcher's license was, but it didn't seem like the right time to ask. "He just said you had big plans, you know... and that you needed credit for completing a keeper's assignment. So did you get it?"

Grover looked down at the naiads. "Mr. D suspended judgment. He said I hadn't failed or succeeded with you yet, so our fates were still tied together. If you got a quest and I went along to protect you, and we both came back alive, then maybe he'd consider the job complete."

My spirits lifted. "Well, that's not so bad, right?"

"Blaa-ha-ha! He might as well have transferred me to stable-cleaning duty. The chances of you getting a quest... and even if you did, why would you want me along?"

"Of course I'd want you along!"

Grover stared glumly into the water. "Basket-weaving... Must be nice to have a useful skill."

I tried to reassure him that he had lots of talents, but that just made him look more miserable. We talked about canoeing and swordplay for a while, then debated the pros and cons of the different gods. Finally, I asked him about the four empty cabins.

"Number eight, the silver one, belongs to Artemis," he said. "She vowed to be a maiden forever. So of course, no kids. The cabin is, you know, honorary. If she didn't have one, she'd be mad."

"Yeah, okay. But the other three, the ones at the end. Are those the Big Three?"

Grover tensed. We were getting close to a touchy subject. "No. One of them, number two, is Hera's," he said. "That's another honorary thing. She's the goddess of marriage, so of course she wouldn't go around having affairs with mortals. That's her husband's job. When we say the Big Three, we mean the three powerful brothers, the sons of Kronos."

"Zeus, Poseidon, Hades."

"Right. You know. After the great battle with the Titans, they took over the world from their dad and drew lots to decide who got what."

"Zeus got the sky," I remembered. "Poseidon the sea, Hades the Underworld."

"Uh-huh."

"But Hades doesn't have a cabin here."

"No. He doesn't have a throne on Olympus, either. He sort of does his own thing down in the Underworld. If he did have a cabin here..." Grover shuddered. "Well, it wouldn't be pleasant. Let's leave it at that."

"But Zeus and Poseidon—they both had, like, a bazillion kids in the myths. Why are their cabins empty?"

Grover shifted his hooves uncomfortably. "About sixty years ago, after World War II, the Big Three agreed they wouldn't sire any more heroes. Their children were just too powerful. They were affecting the course of human events too much, causing too much carnage. World War II, you know, that was basically a fight between the sons of Zeus and Poseidon on one side, and the sons of Hades on the other. The winning side, Zeus and Poseidon, made Hades swear an oath with them: no more affairs with mortal women. They all swore on the River Styx."

Thunder boomed........

I said, "That's the most serious oath you can make."

Grover nodded.

"And the brothers kept their word—no kids?"

Grover's face darkened. "Seventeen years ago, Zeus fell off the wagon. There was this TV starlet with a big fluffy eighties hairdo—he just couldn't help himself. When their child was born, a little girl named Thalia... well, the River Styx is serious about promises. Zeus himself got off easy because he's immortal, but he brought a terrible fate on his daughter."

"But that isn't fair.' It wasn't the little girl's fault."

Grover hesitated. "Percy, children of the Big Three have powers greater than other half-bloods. They have a strong aura, a scent that attracts monsters. When Hades found out about the girl, he wasn't too happy about Zeus breaking his oath. Hades let the worst monsters out of Tartarus to torment Thalia. A satyr was assigned to be her keeper when she was twelve, but there was nothing he could do. He tried to escort her here with a couple of other half-bloods she'd befriended. They almost made it. They got all the way to the top of that hill."

He pointed across the valley, to the pine tree where I'd fought the minotaur. "All three Kindly Ones were after them, along with a horde of hellhounds. They were about to be overrun when Thalia told her satyr to take the other two half-bloods to safety while she held off the monsters. She was wounded and tired, and she didn't want to live like a hunted animal. The satyr didn't want to leave her, but he couldn't change her mind, and he had to protect the others. So Thalia made her final stand alone, at the top of that hill. As she died, Zeus took pity on her. He turned her into that pine tree. Her spirit still helps protect the borders of the valley. That's why the hill is called Half-Blood Hill."

I stared at the pine in the distance.

The story made me feel hollow, and guilty too. A girl my age had sacrificed herself to save her friends. She had faced a whole army of monsters. Next to that, my victory over the Minotaur didn't seem like much. I wondered, if I'd acted differently, could I have saved my mother?

"Grover," I said, "have heroes really gone on quests to the Underworld?"

"Sometimes," he said. "Orpheus. Hercules. Houdini."

"And have they ever returned somebody from the dead?"

"No. Never. Orpheus came close.... Percy, you're not seriously thinking—"

"No," I lied. "I was just wondering. So... a satyr is always assigned to guard a demigod?"

Grover studied me warily. I hadn't persuaded him that I'd really dropped the Underworld idea. "Not always. We go undercover to a lot of schools. We try to sniff out the half-bloods who have the makings of great heroes. If we find one with a very strong aura, like a child of the Big Three, we alert Chiron. He tries to keep an eye on them, since they could cause really huge problems."

"And you found me. Chiron said you thought I might be something special."

Grover looked as if I'd just led him into a trap. "I didn't... Oh, listen, don't think like that. If you were—you know—you'd never ever be allowed a quest, and I'd never get my license. You're probably a child of Hermes. Or maybe even one of the minor gods, like Nemesis, the god of revenge. Don't worry, okay?"

I got the idea he was reassuring himself more than me.

That night after dinner, there was a lot more excitement than usual.

At last, it was time for capture the flag.

When the plates were cleared away, the conch horn sounded and we all stood at our tables.

Campers yelled and cheered as Annabeth and two of her siblings ran into the pavilion carrying a silk banner. It was about ten feet long, glistening gray, with a painting of a barn owl above an olive tree. From the opposite side of the pavilion, Clarisse and her buddies ran in with another banner, of identical size, but gaudy red, painted with a bloody spear and a boar's head.

I turned to Luke and yelled over the noise, "Those are the flags?"

"Yeah."

"Ares and Athena always lead the teams?"

"Not always," he said. "But often."

"So, if another cabin captures one, what do you do— repaint the flag?"

He grinned. "You'll see. First we have to get one."

"Whose side are we on?"

He gave me a sly look, as if he knew something I didn't. The scar on his face made him look almost evil in the torchlight. "We've made a temporary alliance with Athena. Tonight, we get the flag from Ares. And you are going to help."

The teams were announced. Athena had made an alliance with Apollo and Hermes, the two biggest cabins. Apparently, privileges had been traded—shower times, chore schedules, the best slots for activities—in order to win support.

Ares had allied themselves with everybody else: Dionysus, Demeter, Aphrodite, and Hephaestus. From what I'd seen, Dionysus's kids were actually good athletes, but there were only two of them. Demeter's kids had the edge with nature skills and outdoor stuff but they weren't very aggressive. Aphrodite's sons and daughters I wasn't too worried about. They mostly sat out every activity and checked their reflections in the lake and did their hair and gossiped. Hephaestus's kids weren't pretty, and there were only four of them, but they were big and burly from working in the metal shop all day. They might be a problem. That, of course, left Ares's cabin: a dozen of the biggest, ugliest, meanest kids on Long Island, or anywhere else on the planet.

Chiron hammered his hoof on the marble.

"Heroes!" he announced. "You know the rules. The creek is the boundary line. The entire forest is fair game. All magic items are allowed. The banner must be prominently displayed, and have no more than two guards. Prisoners may be disarmed, but may not be bound or gagged. No killing or maiming is allowed. I will serve as referee and battlefield medic. Arm yourselves!"

He spread his hands, and the tables were suddenly covered with equipment: helmets, bronze swords, spears, oxhide shields coated in metal.

"Whoa," I said. "We're really supposed to use these?"

Luke looked at me as if I were crazy. "Unless you want to get skewered by your friends in cabin five. Here—Chiron thought these would fit. You'll be on border patrol."

My shield was the size of an NBA backboard, with a big caduceus in the middle. It weighed about a million pounds. I could have snowboarded on it fine, but I hoped nobody seriously expected me to run fast. My helmet, like all the helmets on Athena's side, had a blue horsehair plume on top. Ares and their allies had red plumes.

Annabeth yelled, "Blue team, forward!"

We cheered and shook our swords and followed her down the path to the south woods. The red team yelled taunts at us as they headed off toward the north.

I managed to catch up with Annabeth without tripping over my equipment. "Hey."

She kept marching.

"So what's the plan?" I asked. "Got any magic items you can loan me?"

Her hand drifted toward her pocket, as if she were afraid I'd stolen something.

"Just watch Clarisse's spear," she said. "You don't want that thing touching you. Otherwise, don't worry. We'll take the banner from Ares. Has Luke given you your job?"

"Border patrol, whatever that means."

"It's easy. Stand by the creek, keep the reds away. Leave the rest to me. Athena always has a plan."

She pushed ahead, leaving me in the dust.

"Okay," I mumbled. "Glad you wanted me on your team."

It was a warm, sticky night. The woods were dark, with fireflies popping in and out of view. Annabeth stationed me next to a little creek that gurgled over some rocks, then she and the rest of the team scattered into the trees.

Standing there alone, with my big blue-feathered helmet and my huge shield, I felt like an idiot. The bronze sword, like all the swords I'd tried so far, seemed balanced wrong. The leather grip pulled on my hand like a bowling ball.

There was no way anybody would actually attack me, would they? I mean, Olympus had to have liability issues, right?

Far away, the conch horn blew. I heard whoops and yells in the woods, the clanking of metal, kids fighting. A blue-plumed ally from Apollo raced past me like a deer, leaped through the creek, and disappeared into enemy territory.

Great, I thought. I'll miss all the fun, as usual.

Then I heard a sound that sent a chill up my spine, a low canine growl, somewhere close by.

I raised my shield instinctively; I had the feeling something was stalking me.

Then the growling stopped. I felt the presence retreating.

On the other side of the creek, the underbrush exploded. Five Ares warriors came yelling and screaming out of the dark.

"Cream the punk!" Clarisse screamed.

Her ugly pig eyes glared through the slits of her helmet. She brandished a five-foot-long spear, its barbed metal tip flickering with red light. Her siblings had only the standard-issue bronze swords—not that that made me feel any better.

They charged across the stream. There was no help in sight. I could run. Or I could defend myself against half the Ares cabin.

I managed to sidestep the first kid's swing, but these guys were not as stupid the Minotaur. They surrounded me, and Clarisse thrust at me with her spear. My shield deflected the point, but I felt a painful tingling all over my body. My hair stood on end. My shield arm went numb, and the air burned.

Electricity. Her stupid spear was electric. I fell back.

Another Ares guy slammed me in the chest with the butt of his sword and I hit the dirt.

They could've kicked me into jelly, but they were too busy laughing.

"Give him a haircut," Clarisse said. "Grab his hair."

I managed to get to my feet. I raised my sword, but Clarisse slammed it aside with her spear as sparks flew. Now both my arms felt numb.

"Oh, wow," Clarisse said. "I'm scared of this guy. Really scared."

"The flag is that way," I told her. I wanted to sound angry, but I was afraid it didn't come out that way.

"Yeah," one of her siblings said. "But see, we don't care about the flag. We care about a guy who made our cabin look stupid."

"You do that without my help," I told them. It probably wasn't the smartest thing to say.

Two of them came at me. I backed up toward the creek, tried to raise my shield, but Clarisse was too fast. Her spear stuck me straight in the ribs. If I hadn't been wearing an armored breastplate, I would've been shish-ke-babbed. As it was, the electric point just about shocked my teeth out of my mouth. One of her cabinmates slashed his sword across my arm, leaving a good-size cut.

Seeing my own blood made me dizzy—warm and cold at the same time.

"No maiming," I managed to say.

"Oops," the guy said. "Guess I lost my dessert privilege.

He pushed me into the creek and I landed with a splash. They all laughed. I figured as soon as they were through being amused, I would die. But then something happened. The water seemed to wake up my senses, as if I'd just had a bag of my mom's double-espresso jelly beans.

Clarisse and her cabinmates came into the creek to get me, but I stood to meet them. I knew what to do. I swung the flat of my sword against the first guy's head and knocked his helmet clean off. I hit him so hard I could see his eyes vibrating as he crumpled into the water.

Ugly Number Two and Ugly Number Three came at me. I slammed one in the face with my shield and used my sword to shear off the other guy's horsehair plume. Both of them backed up quick. Ugly Number Four didn't look really anxious to attack, but Clarisse kept coming, the point of her spear crackling with energy. As soon as she thrust, I caught the shaft between the edge of my shield and my sword, and I snapped it like a twig.

"Ah!" she screamed. "You idiot! You corpse-breath worm!"

She probably would've said worse, but I smacked her between the eyes with my sword-butt and sent her stumbling backward out of the creek.

Then I heard yelling, elated screams, and I saw Luke racing toward the boundary line with the red team's banner lifted high. He was flanked by a couple of Hermes guys covering his retreat, and a few Apollos behind them, fighting off the Hephaestus kids. The Ares folks got up, and Clarisse muttered a dazed curse.

"A trick!" she shouted. "It was a trick."

They staggered after Luke, but it was too late. Everybody converged on the creek as Luke ran across into friendly territory. Our side exploded into cheers. The red banner shimmered and turned to silver. The boar and spear were replaced with a huge caduceus, the symbol of cabin eleven. Everybody on the blue team picked up Luke and started carrying him around on their shoulders. Chiron cantered out from the woods and blew the conch horn.

The game was over. We'd won.

I was about to join the celebration when Annabeth's voice, right next to me in the creek, said, "Not bad, hero."

I looked, but she wasn't there.

"Where the heck did you learn to fight like that?" she asked. The air shimmered, and she materialized, holding a Yankees baseball cap as if she'd just taken it off her head.

I felt myself getting angry. I wasn't even fazed by the fact that she'd just been invisible. "You set me up," I said. "You put me here because you knew Clarisse would come after me, while you sent Luke around the flank. You had it all figured out."

Annabeth shrugged. "I told you. Athena always, always has a plan."

"A plan to get me pulverized."

"I came as fast as I could. I was about to jump in, but..." She shrugged. "You didn't need help."

Then she noticed my wounded arm. "How did you do that?"

"Sword cut," I said. "What do you think?"

"No. It was a sword cut. Look at it."

The blood was gone. Where the huge cut had been, there was a long white scratch, and even that was fading. As I watched, it turned into a small scar, and disappeared.

"I—I don't get it," I said.

Annabeth was thinking hard. I could almost see the gears turning. She looked down at my feet, then at Clarisse's broken spear, and said, "Step out of the water, Percy."

"What—"

"Just do it."

I came out of the creek and immediately felt bone tired. My arms started to go numb again. My adrenaline rush left me. I almost fell over, but Annabeth steadied me.

"Oh, Styx," she cursed. "This is not good. I didn't want... I assumed it would be Zeus...."

Before I could ask what she meant, I heard that canine growl again, but much closer than before. A howl ripped through the forest.

The campers' cheering died instantly. Chiron shouted something in Ancient Greek, which I would realize, only later, I had understood perfectly: "Stand ready! My bow!"

Annabeth drew her sword.

There on the rocks just above us was a black hound the size of a rhino, with lava-red eyes and fangs like daggers.

It was looking straight at me.

Nobody moved except Annabeth, who yelled, "Percy, run!"

She tried to step in front of me, but the hound was too fast. It leaped over her—an enormous shadow with teeth—and just as it hit me, as I stumbled backward and felt its razor-sharp claws ripping through my armor, there was a cascade of thwacking sounds, like forty pieces of paper being ripped one after the other. From the hounds neck sprouted a cluster of arrows. The monster fell dead at my feet.

By some miracle, I was still alive. I didn't want to look underneath the ruins of my shredded armor. My chest felt warm and wet, and I knew I was badly cut. Another second, and the monster would've turned me into a hundred pounds of delicatessen meat.

Chiron trotted up next to us, a bow in his hand, his face grim.

"Di immortales!" Annabeth said. "That's a hellhound from the Fields of Punishment. They don't... they're not supposed to..."

"Someone summoned it," Chiron said. "Someone inside the camp."

Luke came over, the banner in his hand forgotten, his moment of glory gone.

Clarisse yelled, "It's all Percy's fault! Percy summoned it!"

"Be quiet, child," Chiron told her.

We watched the body of the hellhound melt into shadow, soaking into the ground until it disappeared.

"You're wounded," Annabeth told me. "Quick, Percy, get in the water."

"I'm okay."

"No, you're not," she said. "Chiron, watch this."

I was too tired to argue. I stepped back into the creek, the whole camp gathering around me.

Instantly, I felt better. I could feel the cuts on my chest closing up. Some of the campers gasped.

"Look, I—I don't know why," I said, trying to apologize. "I'm sorry...."

But they weren't watching my wounds heal. They were staring at something above my head.

"Percy," Annabeth said, pointing. "Um..."

By the time I looked up, the sign was already fading, but I could still make out the hologram of green light, spinning and gleaming. A three-tipped spear: a trident.

"Your father," Annabeth murmured. "This is really not good."

"It is determined," Chiron announced.

All around me, campers started kneeling, even the Ares cabin, though they didn't look happy about it.

"My father?" I asked, completely bewildered.

"Poseidon," said Chiron. "Earthshaker, Stormbringer, Father of Horses. Hail, Perseus Jackson, Son of the Sea God."