Train to Seward, Alaska

After about an hour, Percy started to relax. They bought hot chocolate from the dining car. The seats were warm and comfortable, and he thought about taking a nap.

Then a shadow passed overhead. Tourists murmured in excitement and started taking pictures.

"Eagle!" one yelled.

"Eagle?" said another.

"Huge eagle!" said a third.

"That's no eagle," Frank said.

Percy looked up just in time to see the creature make a second pass. It was definitely larger than an eagle, with a sleek black body the size of a Labrador retriever. Its wingspan was at least ten feet across.

"There's another one!" Frank pointed. "Strike that. Three, four. Okay, we're in trouble."

The creatures circled the train like vultures, delighting the tourists. Percy wasn't delighted. The monsters had glowing red eyes, sharp beaks, and vicious talons.

Percy felt for his pen in his pocket. "Those things look familiar . . ."

"Seattle," Hazel said. "The Amazons had one in a cage. They're—"

Then several things happened at once. The emergency brake screeched, pitching them forward. Tourists screamed and tumbled through the aisles. The monsters swooped down, shattering the glass roof of the car, and the entire train toppled off the rails.

Percy went weightless. His vision blurred. Claws grabbed his arms and lifted him into the air. Below, train wheels squealed and metal crashed. Glass shattered. Passengers screamed.

When his eyesight cleared, he saw the beast that was carrying him aloft. It had the body of a panther—sleek, black, and feline—with the wings and head of an eagle. Its eyes glowed blood-red.

Percy squirmed. The monster's front talons were wrapped around his arms like steel bands. He couldn't free himself. He rose higher and higher in the cold wind. Percy had no idea where the monster was taking him, but he was pretty sure he wouldn't like it when he got there.

If only he could reach his sword. He might be able to jab the creature, get it to let him go. Then he'd be falling, but the ground below him was covered in snow. It might be enough to cushion his fall. At least the mark of Achilles was keeping the creature's talons from slicing his skin.

He yelled—mostly out of frustration. Then something whistled by his ear. An arrow sprouted from the monster's neck. The creature shrieked and let go.

Percy fell, crashing through tree branches until he slammed into a snowbank. He groaned, looking up at a massive pine tree he'd just shredded. He silently thanked the gods for his thick skin.

He managed to stand. Nothing seemed broken. Frank stood to his left, shooting down the creatures as fast as he could. Hazel was at his back, swinging her sword at any monster that came close, but there were too many swarming around them—at least a dozen.

Percy drew Riptide. He sliced the wing off one monster and sent it spiraling into a tree, then sliced through another that burst into dust. But the defeated ones began to re-form immediately.

"What are these things?" he yelled.

"Gryphons!" Hazel said. "We have to get them away from the train!"

Percy saw what she meant. The train cars had fallen over, and their roofs had shattered. Tourists were stumbling around in shock. Percy didn't see anybody seriously injured, but the gryphons were swooping toward anything that moved. The only thing keeping them away from the mortals was a glowing gray warrior in camouflage—Frank's pet spartus.

Percy glanced over and noticed Frank's spear was gone. "Used your last charge?"

"Yeah." Frank shot another gryphon out of the sky. "I had to help the mortals. The spear just dissolved."

Percy nodded. Part of him was relieved. He didn't like the skeleton warrior. Part of him was disappointed, because that was one less weapon they had at their disposal. But he didn't fault Frank. Frank had done the right thing.

"Let's move the fight!" Percy said. "Away from the tracks!"

They stumbled through the snow, smacking and slicing gryphons that re-formed from dust every time they were killed. Percy took the rear while Frank and Hazel led the way. More than once, Percy had to bodily block an attack to protect his friends. Each time, the gryphons' talons bounced off his skin without harming him, and he thanked his iron skin.

Percy had had no experience with gryphons. He'd always imagined them as huge noble animals, like lions with wings, but these things reminded him more of vicious pack hunters—flying hyenas.

About fifty yards from the tracks, the trees gave way to an open marsh. The ground was so spongy and icy, Percy felt like he was racing across Bubble Wrap. Frank was running out of arrows. Hazel was breathing hard. Percy's own sword swings were getting slower. He realized they were alive only because the gryphons weren't trying to kill them. The gryphons wanted to pick them up and carry them off somewhere.

Maybe to their nests, Percy thought.

It became easier to let the gryphons hit him than to fight them off every time. If one managed to grab him like it meant to carry him away again, he just stabbed it with Riptide and it backed off.

Percy felt a shiver run down his spine and instinctively rolled. A gryphon crashed into the snow where he had just been standing, and he realized it would have hit him right in the small of his back. As he realized that, he remembered something else from his past, something very important—where his mortal spot was.

Percy shivered again, realizing how close to death he'd come. He had no armor, nothing to protect him besides his sword. He made a silent vow to stop using himself as a shield. Until he got some armor, one lucky strike was all it would take to do him in.

Then Percy tripped over something in the tall grass—a circle of scrap metal about the size of a tractor tire. It was a massive bird's nest—a gryphon's nest—the bottom littered with old pieces of jewelry, an Imperial gold dagger, a dented centurion's badge, and two pumpkin-sized eggs that looked like real gold.

Percy jumped into the nest. He pressed his sword tip against one of the eggs. "Back off, or I break it!"

The gryphons squawked angrily. They buzzed around the nest and snapped their beaks, but they didn't attack. Hazel and Frank stood back to back with Percy, their weapons ready.

"Gryphons collect gold," Hazel said. "They're crazy for it. Look—more nests over there."

Frank nocked his last arrow. "So if these are their nests, where were they trying to take Percy? That thing was flying away with him."

Percy's arms still throbbed where the gryphon had grabbed him. "Alcyoneus," he guessed. "Maybe they're working for him. Are these things smart enough to take orders?"

"I don't know," Hazel said. "I never fought them when I lived here. I just read about them at camp."

"Weaknesses?" Frank asked. "Please tell me they have weaknesses."

Hazel scowled. "Horses. They hate horses—natural enemies, or something. I wish Arion was here!"

The gryphons shrieked. They swirled around the nest with their red eyes glowing.

"Guys," Frank said nervously, "I see legion relics in this nest."

"I know," Percy said.

"That means other demigods died here, or—"

"Frank, it'll be okay," Percy promised.

One of the gryphons dived in. Percy raised his sword, ready to stab the egg. The monster veered off, but the other gryphons were losing their patience. Percy couldn't keep this standoff going much longer.

He glanced around the fields, desperately trying to formulate a plan. About a quarter mile away, a Hyperborean giant was sitting in the bog, peacefully picking mud from between his toes with a broken tree trunk.

"I've got an idea," Percy said. "Hazel—all the gold in these nests. Do you think you can use it to cause a distraction?"

"I—I guess."

"Just give us enough time for a head start. When I say go, run for that giant."

Frank gaped at him. "You want us to run toward a giant?"

"Trust me," Percy said. "Ready? Go!"

Hazel thrust her hand upward. From a dozen nests across the marsh, golden objects shot into the air—jewelry, weapons, coins, gold nuggets, and most importantly, gryphon eggs. The monsters shrieked and flew after their eggs, frantic to save them.

Percy and his friends ran. Their feet splashed and crunched through the frozen marsh. Percy poured on speed, but he could hear the gryphons closing behind them, and now the monsters were really angry.

Percy was at the rear again, which meant he was the gryphons' closest target. He heard the screech right behind him before he felt it—a gryphon slammed into him and sent him flying off his feet, its talons raking through the back of his shirt. He felt the icy talons on his skin, but thankfully, they missed his weak spot. He landed in the snow with an oomph and saw shadows closing in on him, probably to try to carry him off again. He rolled onto his back in an attempt to fight them off and protect his weak spot.

And then Frank and Hazel were there, swiping at the gryphons and yanking Percy back to his feet.

"You okay?" Frank shouted as they continued running.

"Fine, just keep going!" Percy yelled.

Percy was already bone-tired from the fight. Why did that keep happening? His memory wasn't entirely back yet. All he knew was that it had something to do with the mark of Achilles.

The giant hadn't noticed the commotion yet. He was inspecting his toes for mud, his face sleepy and peaceful, his white whiskers glistening with ice crystals. Around his neck was a necklace of found objects—garbage cans, car doors, moose antlers, camping equipment, even a toilet. Apparently, he'd been cleaning up the wilderness.

Percy hated to disturb him, especially since it meant taking shelter under the giant's thighs, but they didn't have much choice.

"Under!" he told his friends. "Crawl under!"

They scrambled between the massive blue legs and flattened themselves in the mud, crawling as close as they could to his loincloth. Percy tried to breathe through his mouth, but it wasn't the most pleasant hiding spot.

"What's the plan?" Frank hissed. "Get flattened by a blue rump?"

"Lay low," Percy said. "Only move if you have to."

The gryphons arrived in a wave of angry beaks, talons, and wings, swarming around the giant, trying to get under his legs.

The giant rumbled in surprise. He shifted. Percy had to roll to avoid getting crushed by his large hairy rear. The Hyperborean grunted, a little more irritated. He swatted at the gryphons, but they squawked in outrage and began pecking at his legs and hands.

"Ruh?" the giant bellowed. "Ruh!"

He took a deep breath and blew out a wave of cold air. Even under the protection of the giant's legs, Percy could feel the temperature drop. The gryphons' shrieking stopped abruptly, replaced by the thunk, thunk, thunk of heavy objects hitting the mud.

"Come on," Percy told his friends. "Carefully."

They squirmed out from under the giant. All around the marsh, trees were glazed with frost. A huge swath of the bog was covered in fresh snow. Frozen gryphons stuck out of the ground like feathery Popsicle sticks, their wings still spread, beaks open, eyes wide with surprise.

Percy and his friends scrambled away, trying to keep out of the giant's vision, but the big guy was too busy to notice them. He was trying to figure out how to string a frozen gryphon onto his necklace.

"Percy . . ." Hazel wiped the ice and mud from her face. "How did you know the giant could do that?"

"I almost got hit by Hyperborean breath once," he said, remembering bits and pieces of a battle beneath the Empire State Building in New York. A girl encased in a block of ice. "We'd better move. The gryphons won't stay frozen forever."

Frank and Hazel were both shocked that Percy was unharmed after all that. He waved off their concerns and traded out his shredded shirt for a new one. It would rip as easily as the last one had, but he felt better with something covering his back. Still, he gripped Riptide tightly in his pocket, just in case. He needed to be ready.