I closed my eyes.

"What are you doing, Jackson?" hissed Dr. Thorn. "Keep moving!"

I opened my eyes and kept shuffling forward. "It's my shoulder," I lied, trying to sound miserable, which wasn't hard. "It burns."

"Bah! My poison causes pain. It will not kill you. Walk!"

Thorn herded us outside, and I tried to concentrate. I pictured Grover's face. I focused on my feelings of fear and danger. Last summer, Grover had created an empathy link between us. He'd sent me visions in my dreams to let me know when he was in trouble. As far as I knew, we were still linked, but I'd never tried to contact Grover before. I didn't even know if it would work while Grover was awake.

Hey, Grover! I thought. Thorn's kidnapping us! He's a poisonous spike-throwing maniac! Help!

Thorn inarched us into the woods. We took a snowy path dimly lit by old-fashioned lamplights. My shoulder ached. The wind blowing through my ripped clothes was so cold that I felt like a Percysicle.

"There is a clearing ahead," Thorn said. "We will summon your ride."

"What ride?" Bianca demanded. "Where are you taking us?"

"Silence, you insufferable girl!"

"Don't talk to my sister that way.'" Nico said. His voice quivered, but I was impressed that he had the guts to say anything at all.

Dr. Thorn made a growling sound that definitely wasn't human. It made the hairs stand up on the back of my neck, but I forced myself to keep walking and pretend I was being a good little captive. Meanwhile, I projected my thoughts like crazy—anything to get Grover's attention: Grover! Apples! Tin cans! Get your furry goat behind out here and bring some heavily armed friends!

"Halt," Thorn said.

The woods had opened up. We'd reached a cliff overlooking the sea. At least, I sensed the sea was down there, hundreds of feet below. I could hear the waves churning and I could smell the cold salty froth. But all I could see was mist and darkness.

Dr. Thorn pushed us toward the edge. I stumbled, and Bianca caught me.

"Thanks," I murmured.

"What is he?" she whispered. "How do we fight him?"

"I… I'm working on it."

"I'm scared," Nico mumbled. He was fiddling with something—a little metal toy soldier of some kind.

"Stop talking!" Dr. Thorn said. "Face me!"

We turned.

Thorn's two-tone eyes glittered hungrily. He pulled something from under his coat. At first I thought it was a switchblade, but it was only a phone. He pressed the side button and said, "The package—it is ready to deliver."

There was a garbled reply, and I realized Thorn was in walkie-talkie mode. This seemed way too modern and creepy—a monster using a mobile phone.

I glanced behind me, wondering how far the drop was.

Dr. Thorn laughed. "By all means, Son of Poseidon. Jump!There is the sea. Save yourself."

"What did he call you?" Bianca muttered.

"I'll explain later," I said.

"You do have a plan, right?"

Grover! I thought desperately. Come to me!

Maybe I could get both the di Angelos to jump with me into the ocean. If we survived the fall, I could use the water to protect us. I'd done things like that before. If my dad was in a good mood, and listening, he might help. Maybe.

"I would kill you before you ever reached the water," Dr. Thorn said, as if reading my thoughts. "You do not realize who I am, do you?"

A flicker of movement behind him, and another missile whistled so close to me that it nicked my ear. Something had sprung up behind Dr. Thorn—like a catapult, but more flexible… almost like a tail.

"Unfortunately," Thorn said, "you are wanted alive, if possible. Otherwise you would already be dead."

"Who wants us?" Bianca demanded. "Because if you think you'll get a ransom, you're wrong. We don't have any family. Nico and I…" Her voice broke a little. "We've got no one but each other."

"Aww," Dr. Thorn said. "Do not worry, little brats. You will be meeting my employer soon enough. Then you will have a brand-new family."

"Luke," I said. "You work for Luke."

Dr. Thorn's mouth twisted with distaste when I said the name of my old enemy—a former friend who'd tried to kill me several times. "You have no idea what is happening, Perseus Jackson. I will let the General enlighten you. You are going to do him a great service tonight. He is looking forward to meeting you."

"The General?" I asked. Then I realized I'd said it with a French accent. "I mean… who's the General?"

Thorn looked toward the horizon. "Ah, here we are. Your transportation."

I turned and saw a light in the distance, a searchlight over the sea. Then I heard the chopping of helicopter blades getting louder and closer.

"Where are you taking us?" Nico said.

"You should be honored, my boy. You will have the opportunity to join a great army! Just like that silly game you play with cards and dolls."

"They're not dolls! They're figurines! And you can take your great army and—"

"Now, now," Dr. Thorn warned. "You will change your mind about joining us, my boy. And if you do not, well… there are other uses for half-bloods. We have many monstrous mouths to feed. The Great Stirring is underway."

"The Great what?" I asked. Anything to keep him talking while I tried to figure out a plan.

"The stirring of monsters." Dr. Thorn smiled evilly. "The worst of them, the most powerful, are now waking. Monsters that have not been seen in thousands of years. They will cause death and destruction the likes of which mortals have never known. And soon we shall have the most important monster of all—the one that shall bring about the downfall of Olympus!"

"Okay," Bianca whispered to me. "He's completely nuts."

"We have to jump off the cliff," I told her quietly. "Into the sea."

"Oh, super idea. You're completely nuts, too."

I never got the chance to argue with her, because just then an invisible force slammed into me.

Looking back on it, Annabeth's move was brilliant. Wearing her cap of invisibility, she plowed into the di Angelos and me, knocking us to the ground. For a split second, Dr. Thorn was taken by surprise, so his first volley of missiles zipped harmlessly over our heads. This gave Thalia and Grover a chance to advance from behind—Thalia wielding her magic shield, Aegis.

If you've never seen Thalia run into battle, you have never been truly frightened. She uses a huge spear that expands from this collapsible Mace canister she carries in her pocket, but that's not the scary part. Her shield is modeled after one her dad Zeus uses—also called Aegis—a gift from Athena. The shield has the head of the gorgon Medusa molded into the bronze, and even though it won't turn you to stone, it's so horrible, most people will panic and run at the sight of it.

Even Dr. Thorn winced and growled when he saw it.

Thalia moved in with her spear. "For Zeus!"

I thought Dr. Thorn was a goner. Thalia jabbed at his head, but he snarled and swatted the spear aside. His hand changed into an orange paw, with enormous claws that sparked against Thalia's shield as he slashed. If it hadn't been for Aegis, Thalia would've been sliced like a loaf of bread. As it was, she managed to roll backward and land on her feet.

The sound of the helicopter was getting louder behind me, but I didn't dare look.

Dr. Thorn launched another volley of missiles at Thalia, and this time I could see how he did it. He had a tail—a leathery, scorpionlike tail that bristled with spikes at the tip. The missiles deflected off Aegis, but the force of their impact knocked Thalia down.

Grover sprang forward. He put his reed pipes to his lips and began to play—a frantic jig that sounded like something pirates would dance to. Grass broke through the snow. Within seconds, rope-thick weeds were wrapping around Dr. Thorn's legs, entangling him.

Dr. Thorn roared and began to change. He grew larger until he was in his true form—his face still human, but his body that of a huge lion. His leathery, spiky tail whipped deadly thorns in all directions.

"A manticore!" Annabeth said, now visible. Her magical New York Yankees cap had come off when she'd plowed into us.

"Who are you people?" Bianca di Angelo demanded. "And what is that?"

"A manticore?" Nico gasped. "He's got three thousand attack power and plus five to saving throws!"

I didn't know what he was talking about, but I didn't have time to worry about it. The manticore clawed Grover's magic weeds to shreds then turned toward us with a snarl.

"Get down!" Annabeth pushed the di Angelos flat into the snow. At the last second, I remembered my own shield. I hit my wristwatch, and metal plating spiraled out into a thick bronze shield. Not a moment too soon. The thorns impacted against it with such force they dented the metal. The beautiful shield, a gift from my brother, was badly damaged. I wasn't sure it would even stop a second volley.

I heard a thwack and a yelp, and Grover landed next to me with a thud.

"Yield!" the monster roared.

"Never!" Thalia yelled from across the field. She charged the monster, and for a second, I thought she would run him through. But then there was a thunderous noise and a blaze of light from behind us. The helicopter appeared out of the mist, hovering just beyond the cliffs. It was a sleek black military-style gunship, with attachments on the sides that looked like laser-guided rockets. The helicopter had to be manned by mortals, but what was it doing here? How could mortals be working with a monster? The searchlights blinded Thalia, and the manticore swatted her away with its tail. Her shield flew off into the snow. Her spear flew in the other direction.

"No!" I ran out to help her. I parried away a spike just before it would've hit her chest. I raised my shield over us, but I knew it wouldn't be enough.

Dr. Thorn laughed. "Now do you see how hopeless it is? Yield, little heroes."

We were trapped between a monster and a fully armed helicopter. We had no chance.

Then I heard a clear, piercing sound: the call of a hunting horn blowing in the woods.

The manticore froze. For a moment, no one moved. There was only the swirl of snow and wind and the chopping of the helicopter blades.

"No," Dr. Thorn said. "It cannot be—"

His sentence was cut short when something shot past me like a streak of moonlight. A glowing silver arrow sprouted from Dr. Thorn's shoulder.

He staggered backward, wailing in agony.

"Curse you!" Thorn cried. He unleashed his spikes, dozens of them at once, into the woods where the arrow had come from, but just as fast, silvery arrows shot back in reply. It almost looked like the arrows had intercepted the thorns in midair and sliced them in two, but my eyes must've been playing tricks on me. No one, not even Apollo's kids at camp, could shoot with that much accuracy.

The manticore pulled the arrow out of his shoulder with a howl of pain. His breathing was heavy. I tried to swipe at him with my sword, but he wasn't as injured as he looked. He dodged my attack and slammed his tail into my shield, knocking me aside.

Then the archers came from the woods. They were girls, about a dozen of them. The youngest was maybe ten. The oldest, about fourteen, like me. They wore silvery ski parkas and jeans, and they were all armed with bows. They advanced on the manticore with determined expressions.