Again Frank wondered about Nico’s past, but he was afraid to ask. He caught Hazel’s eye.

Go ahead, she seemed to be saying. Nico needs practice talking to people.

The sounds of assault rifles and atom bombs got louder in Frank’s head. Mars and Ares were trying to outsing each other with “Dixie” and “The Battle Hymn of the Republic.” Frank did his best to push that aside.

“Nico, your mom was Italian?” he guessed. “She was from Venice?”

Nico nodded reluctantly. “She met Hades here, back in the 1930s. As World War Two got closer, she fled to the U.S. with my sister and me. I mean…Bianca, my other sister. I don’t remember much about Italy, but I can still speak the language.”

Frank tried to think of a response. Oh, that’s nice didn’t seem to cut it.

He was hanging out with not one but two demigods who’d been pulled out of time. They were both, technically, about seventy years older than he was.

“Must’ve been hard on your mom,” Frank said. “I guess we’ll do anything for someone we love.”

Hazel squeezed his hand appreciatively. Nico stared at the cobblestones. “Yeah,” he said bitterly. “I guess we will.”

Frank wasn’t sure what Nico was thinking. He had a hard time imagining Nico di Angelo acting out of love for anybody, except maybe Hazel. But Frank decided he’d gone as far as he dared with the personal questions.

“So, the lemures…” He swallowed. “How do we avoid them?”

“I’m already on it,” Nico said. “I’m sending out the message that they should stay away and ignore us. Hopefully that’s enough. Otherwise…things could get messy.”

Hazel pursed her lips. “Let’s get going,” she suggested.

Halfway across the piazza, everything went wrong; but it had nothing to do with ghosts.

They were skirting the well in the middle of the square, trying to give the cow monsters some distance, when Hazel stumbled on a loose piece of cobblestone. Frank caught her. Six or seven of the big gray beasts turned to look at them. Frank glimpsed a glowing green eye under one’s mane, and instantly he was hit with a wave of nausea, the way he felt when he ate too much cheese or ice cream.

The creatures made deep throbbing sounds in their throats like angry foghorns.

“Nice cows,” Frank murmured. He put himself between his friends and the monsters. “Guys, I’m thinking we should back out of here slowly.”

“I’m such a klutz,” Hazel whispered. “Sorry.”

“It’s not your fault,” Nico said. “Look at your feet.”

Frank glanced down and caught his breath.

Under their shoes, the paving stones were moving—spiky plant tendrils were pushing up from the cracks.

Nico stepped back. The roots snaked out in his direction, trying to follow. The tendrils got thicker, exuding a steamy green vapor that smelled of boiled cabbage.

“These roots seem to like demigods,” Frank noted.

Hazel’s hand drifted to her sword hilt. “And the cow creatures like the roots.”

The entire herd was now looking their direction, making foghorn growls and stamping their hooves. Frank understood animal behavior well enough to get the message: You are standing on our food. That makes you enemies.

Frank tried to think. There were too many monsters to fight. Something about their eyes hidden under those shaggy manes…Frank had gotten sick from the barest glimpse. He had a bad feeling that if those monsters made direct eye contact, he might get a lot worse than nauseous.

“Don’t meet their eyes,” Frank warned. “I’ll distract them. You two back up slowly toward that black house.”

The creatures tensed, ready to attack.

“Never mind,” Frank said. “Run!”

As it turned out, Frank could not turn into a rhino, and he lost valuable time trying.

Nico and Hazel bolted for the side street. Frank stepped in front of the monsters, hoping to keep their attention. He yelled at the top of his lungs, imagining himself as a fearsome rhinoceros, but with Ares and Mars screaming in his head, he couldn’t concentrate. He remained regular-old Frank.

Two of the cow monsters peeled off from the herd to chase Nico and Hazel.

“No!” Frank yelled after them. “Me! I’m the rhino!”

The rest of the herd surrounded Frank. They growled, emerald-green gas billowing from their nostrils. Frank stepped back to avoid the stuff, but the stench nearly knocked him over.

Okay, so not a rhino. Something else. Frank knew he had only seconds before the monsters trampled or poisoned him, but he couldn’t think. He couldn’t hold the image of any animal long enough to change form.

Then he glanced up at one of the town-house balconies and saw a stone carving—the symbol of Venice.

The next instant, Frank was a full-grown lion. He roared in challenge, then sprang from the middle of the monster herd and landed eight meters away, on top of the old stone well.

The monsters growled in reply. Three of them sprang at once, but Frank was ready. His lion reflexes were built for speed in combat.

He slashed the first two monsters into dust with his claws, then sank his fangs into the third one’s throat and tossed it aside.

There were seven left, plus the two chasing his friends. Not great odds, but Frank had to keep the bulk of herd focused on him. He roared at the monsters, and they edged away.

They outnumbered him, yes. But Frank was a top-of-the-chain predator. The herd monsters knew it. They had also just watched him send three of their friends to Tartarus.

He pressed his advantage and leaped off the well, still baring his fangs. The herd backed off.

If he could just maneuver around them, then turn and run after his friends…

He was doing all right, until he took his first backward step toward the arch. One of cows, either the bravest or the stupidest, took that as a sign of weakness. It charged and blasted Frank in the face with green gas.

He slashed the monster to dust, but the damage was already done. He forced himself not to breathe. Regardless, he could feel the fur burning off his snout. His eyes stung. He staggered back, half-blind and dizzy, dimly aware of Nico screaming his name.

“Frank! Frank!”

He tried to focus. He was back in human form, retching and stumbling. His face felt like it was peeling off. In front of him, the green cloud of gas floated between him and the herd. The remaining cow monsters eyed him warily, probably wondering if Frank had any more tricks up his sleeve.

He glanced behind him. Under the stone arch, Nico di Angelo was holding his black Stygian iron sword, gesturing at Frank to hurry. At Nico’s feet, two puddles of darkness stained the pavement—no doubt the remains of the cow monsters that had chased them.

And Hazel…she was propped against the wall behind her brother. She wasn’t moving.

Frank ran toward them, forgetting about the monster herd. He rushed past Nico and grabbed Hazel’s shoulders. Her head slumped against her chest.

“She got a blast of green gas right in the face,” Nico said miserably. “I—I wasn’t fast enough.”

Frank couldn’t tell if she was breathing. Rage and despair battled inside him. He’d always been scared of Nico. Now he wanted to drop-kick the son of Hades into the nearest canal. Maybe that wasn’t fair, but Frank didn’t care. Neither did the war gods screaming in his head.

“We need to get her back to the ship,” Frank said.

The cow monster herd prowled cautiously just beyond the archway. They bellowed their foghorn cries. From nearby streets, more monsters answered. Reinforcements would soon have the demigods surrounded.

“We’ll never make it on foot,” Nico said. “Frank, turn into a giant eagle. Don’t worry about me. Get her back to the Argo II!”

With his face burning and the voices screaming in his mind, Frank wasn’t sure he could change shape; but he was about to try when a voice behind them said, “Your friends can’t help you. They don’t know the cure.”

Frank spun. Standing in the threshold of the Black House was a young man in jeans and a denim shirt. He had curly black hair and a friendly smile, though Frank doubted he was friendly. Probably he wasn’t even human.

At the moment, Frank didn’t care.

“Can you cure her?” he asked.

“Of course,” the man said. “But you’d better hurry inside. I think you’ve angered every katobleps in Venice.”

THEY BARELY MADE IT INSIDE.

As soon as their host threw the bolts, the cow monsters bellowed and slammed into the door, making it shudder on its hinges.

“Oh, they can’t get in,” the man in denim promised. “You’re safe now!”

“Safe?” Frank demanded. “Hazel is dying!”

Their host frowned as if he didn’t appreciate Frank ruining his good mood. “Yes, yes. Bring her this way.”

Frank carried Hazel as they followed the man farther into the building. Nico offered to help, but Frank didn’t need it. Hazel weighed nothing, and Frank’s body hummed with adrenaline. He could feel Hazel shivering, so at least he knew she was alive; but her skin was cold. Her lips had taken on a greenish tinge—or was that just Frank’s blurry vision?

His eyes still burned from the monster’s breath. His lungs felt like he’d inhaled a flaming cabbage. He didn’t know why the gas had affected him less than it had Hazel. Maybe she’d gotten more of it in her lungs. He would have given anything to change places if it meant saving her.

The voices of Mars and Ares yelled in his head, urging him to kill Nico and the man in denim and anyone else he could find, but Frank forced down the noise.

The house’s front room was some sort of greenhouse. The walls were lined with tables of plant trays under fluorescent lights. The air smelled of fertilizer solution. Maybe Venetians did their gardening inside, since they were surrounded by water instead of soil? Frank wasn’t sure, but he didn’t spend much time worrying about it.

The back room looked like a combination garage, college dorm, and computer lab. Against the left wall glowed a bank of servers and laptops, their screen savers flashing pictures of plowed fields and tractors. Against the right wall sat a single bed, a messy desk, and an open wardrobe filled with extra denim clothes and a stack of farm implements, like pitchforks and rakes.

The back wall was a huge garage door. Parked next to it was a red-and-gold chariot with an open carriage and a single axle, like the chariots Frank had raced at Camp Jupiter. Sprouting from the sides of the driver’s box were giant feathery wings. Wrapped around the rim of the left wheel, a spotted python snored loudly.

Frank hadn’t known that pythons could snore. He hoped he hadn’t done that himself in python form last night.

“Set your friend here,” said the man in denim.

Frank placed Hazel gently on the bed. He removed her sword and tried to make her comfortable, but she was as limp as a scarecrow. Her complexion definitely had a greenish tint.

“What were those cow things?” Frank demanded. “What did they do to her?”

“Katoblepones,” said their host. “Singular: katobleps. In English, it means down-looker. Called that because—”