“And promising to lead us to Epirus.” Frank nodded. “I get the feeling Nico doesn’t play well with others.”

Frank stood up straight. He was wearing a beige T-shirt with a picture of a horse and the words PALIO DI SIENA. He’d only bought it a couple of days ago, but now it was too small. When he stretched, his midriff was exposed.

Hazel realized she was staring. She quickly looked away, her face flushed.

“Nico is my only relative,” she said. “He’s not easy to like, but…thanks for being kind to him.”

Frank smiled. “Hey, you put up with my grandmother in Vancouver. Talk about not easy to like.”

“I loved your grandmother!”

Gale the polecat scampered up to them, farted, and ran away.

“Ugh.” Frank waved away the smell. “Why is that thing here, anyway?”

Hazel was almost glad she wasn’t on dry land. As agitated as she felt, gold and gems would probably be popping up all around her feet.

“Hecate sent Gale to observe,” she said.

“Observe what?”

Hazel tried to take comfort in Frank’s presence, his new aura of solidity and strength.

“I don’t know,” she said at last. “Some kind of test.”

Suddenly the boat lurched forward.

HAZEL AND FRANK TUMBLED OVER EACH OTHER. Hazel accidentally gave herself the Heimlich maneuver with the pommel of her sword and curled on the deck, moaning and coughing up the taste of katobleps poison.

Through a fog of pain, she heard the ship’s figurehead, Festus the bronze dragon, creaking in alarm and shooting fire.

Dimly, Hazel wondered if they’d hit an iceberg—but in the Adriatic, in the middle of summer?

The ship rocked to port with a massive commotion, like telephone poles snapping in half.

“Gahh!” Leo yelled somewhere behind her. “It’s eating the oars!”

What is? Hazel wondered. She tried to stand, but something large and heavy was pinning her legs. She realized it was Frank, grumbling as he tried to extract himself from a pile of loose rope.

Everyone else was scrambling. Jason jumped over them, his sword drawn, and raced toward the stern. Piper was already on the quarterdeck, shooting food from her cornucopia and yelling, “Hey! HEY! Eat this, ya stupid turtle!”

Turtle?

Frank helped Hazel to her feet. “You okay?”

“Yeah,” Hazel lied, clutching her stomach. “Go!”

Frank sprinted up the steps, slinging off his backpack, which instantly transformed into a bow and quiver. By the time he reached the helm, he had already fired one arrow and was nocking the second.

Leo frantically worked the ship’s controls. “Oars won’t retract. Get it away! Get it away!”

Up in the rigging, Nico’s face was slack with shock.

“Styx—it’s huge!” he yelled. “Port! Go port!”

Coach Hedge was the last one on deck. He compensated for that with enthusiasm. He bounded up the steps, waving his baseball bat, and without hesitation goat-galloped to the stern and leaped over the rail with a gleeful “Ha-HA!”

Hazel staggered toward the quarterdeck to join her friends. The boat shuddered. More oars snapped, and Leo yelled, “No, no, no! Dang slimy-shelled son of a mother!”

Hazel reached the stern and couldn’t believe what she saw.

When she heard the word turtle, she thought of a cute little thing the size of a jewelry box, sitting on a rock in the middle of a fishpond. When she heard huge, her mind tried to adjust—okay, perhaps it was like the Galapagos tortoise she’d seen in the zoo once, with a shell big enough to ride on.

She did not envision a creature the size of an island. When she saw the massive dome of craggy black and brown squares, the word turtle simply did not compute. Its shell was more like a landmass—hills of bone, shiny pearl valleys, kelp and moss forests, rivers of seawater trickling down the grooves of its carapace.

On the ship’s starboard side, another part of the monster rose from the water like a submarine.

Lares of Rome…was that its head?

Its gold eyes were the size of wading pools, with dark sideways slits for pupils. Its skin glistened like wet army camouflage—brown flecked with green and yellow. Its red, toothless mouth could’ve swallowed the Athena Parthenos in one bite.

Hazel watched as it snapped off half a dozen oars.

“Stop that!” Leo wailed.

Coach Hedge clambered around the turtle’s shell, whacking at it uselessly with his baseball bat and yelling, “Take that! And that!”

Jason flew from the stern and landed on the creature’s head. He stabbed his golden sword straight between its eyes, but the blade slipped sideways, as if the turtle’s skin were greased steel. Frank shot arrows at the monster’s eyes with no success. The turtle’s filmy inner eyelids blinked with uncanny precision, deflecting each shot. Piper shot cantaloupes into the water, yelling, “Fetch, ya stupid turtle!” But the turtle seemed fixated on eating the Argo II.

“How did it get so close?” Hazel demanded.

Leo threw his hands up in exasperation. “Must be that shell. Guess it’s invisible to sonar. It’s a freaking stealth turtle!”

“Can the ship fly?” Piper asked.

“With half our oars broken off?” Leo punched some buttons and spun his Archimedes sphere. “I’ll have to try something else.”

“There!” Nico yelled from above. “Can you get us to those straits?”

Hazel looked where he was pointing. About half a mile to the east, a long strip of land ran parallel to the coastal cliffs. It was hard to be sure from a distance, but the stretch of water between them looked to be only twenty or thirty yards across—possibly wide enough for the Argo II to slip through, but definitely not wide enough for the giant turtle’s shell.

“Yeah. Yeah.” Leo apparently understood. He turned the Archimedes sphere. “Jason, get away from that thing’s head! I have an idea!”

Jason was still hacking away at the turtle’s face, but when he heard Leo say I have an idea, he made the only smart choice. He flew away as fast as possible.

“Coach, come on!” Jason said.

“No, I got this!” Hedge said, but Jason grabbed him around the waist and took off. Unfortunately, the coach struggled so much that Jason’s sword fell out of his hand and splashed into the sea.

“Coach!” Jason complained.

“What?” Hedge said. “I was softening him up!”

The turtle head-butted the hull, almost tossing the whole crew off the port side. Hazel heard a cracking sound, like the keel had splintered.

“Just another minute,” Leo said, his hands flying over the console.

“We might not be here in another minute!” Frank fired his last arrow.

Piper yelled at the turtle, “Go away!”

For a moment, it actually worked. The turtle turned from the ship and dipped its head underwater. But then it came right back and rammed them even harder.

Jason and Coach Hedge landed on the deck.

“You all right?” Piper asked.

“Fine,” Jason muttered. “Without a weapon, but fine.”

“Fire in the shell!” Leo cried, spinning his Wii controller.

Hazel thought the stern had exploded. Jets of fire blasted out behind them, washing over the turtle’s head. The ship shot forward and threw Hazel to the deck again.

She hauled herself up and saw that the ship was bouncing over the waves at incredible speed, trailing fire like a rocket. The turtle was already a hundred yards behind them, its head charred and smoking.

The monster bellowed in frustration and started after them, its paddle feet scooping through the water with such power that it actually started to gain on them. The entrance to the straits was still a quarter mile ahead.

“A distraction,” Leo muttered. “We’ll never make it unless we get a distraction.”

“A distraction,” Hazel repeated.

She concentrated and thought: Arion!

She had no idea whether it would work. But instantly, Hazel spotted something on the horizon—a flash of light and steam. It streaked across the surface of the Adriatic. In a heartbeat, Arion stood on the quarterdeck.

Gods of Olympus, Hazel thought. I love this horse.

Arion snorted as if to say, Of course you do. You’re not stupid.

Hazel climbed on his back. “Piper, I could use that charmspeak of yours.”

“Once upon a time, I liked turtles,” Piper muttered, accepting a hand up. “Not anymore!”

Hazel spurred Arion. He leaped over the side of the boat, hitting the water at a full gallop.

The turtle was a fast swimmer, but it couldn’t match Arion’s speed. Hazel and Piper zipped around the monster’s head, Hazel slicing with her sword, Piper shouting random commands like, “Dive! Turn left! Look behind you!”

The sword did no damage. Each command only worked for a moment, but they were making the turtle very annoyed. Arion whinnied derisively as the turtle snapped at him, only to get a mouthful of horse vapor.

Soon the monster had completely forgotten the Argo II. Hazel kept stabbing at its head. Piper kept yelling commands and using her cornucopia to bounce coconuts and roasted chickens off the turtle’s eyeballs.

As soon as the Argo II had passed into the straits, Arion broke off his harassment. They sped after the ship, and a moment later were back on deck.

The rocket fire had extinguished, though smoking bronze exhaust vents still jutted from the stern. The Argo II limped forward under sail power, but their plan had paid off. They were safely harbored in the narrow waters, with a long, rocky island to starboard and the sheer white cliffs of the mainland to port. The turtle stopped at the entrance to the straits and glared at them balefully, but it made no attempt to follow. Its shell was obviously much too wide.

Hazel dismounted and got a big hug from Frank. “Nice work out there!” he said.

Her face flushed. “Thanks.”

Piper slid down next to her. “Leo, since when do we have jet propulsion?”

“Aw, you know…” Leo tried to look modest and failed. “Just a little something I whipped up in my spare time. Wish I could give you more than a few seconds of burn, but at least it got us out of there.”

“And roasted the turtle’s head,” Jason said appreciatively. “So what now?”

“Kill it!” Coach said. “You even have to ask? We got enough distance. We got ballistae. Lock and load, demigods!”

Jason frowned. “Coach, first of all, you made me lose my sword.”

“Hey! I didn’t ask for an evac!”

“Second, I don’t think the ballistae will do any good. That shell is like Nemean Lion skin. Its head isn’t any softer.”

“So we chuck one right down its throat,” Coach said, “like you guys did with that shrimp monster thing in the Atlantic. Light it up from the inside.”

Frank scratched his head. “Might work. But then you’ve got a five-million-kilo turtle carcass blocking the entrance to the straits. If we can’t fly with the oars broken, how do we get the ship out?”