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 metres 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 manoeuvre around them, then turn and run after his friends ...

He was doing all right, until he took his first backwards step towards 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 ground 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 towards 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 ca.n.a.l. Maybe that wasn't fair, but Frank didn't care. Neither did the war G.o.ds 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 demiG.o.ds 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 round. Standing on 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.'

XIX.

FRANK.

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 further into the building. Nico offered to help, but Frank didn't need it. Hazel weighed nothing, and Frank's body hummed with adrenalin. 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 got 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 ploughed fields and tractors. Against the right wall was 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 '

'They're always looking down.' Nico smacked his forehead. 'Right. I remember reading about them.'

Frank glared at him. 'Now you remember?'

Nico hung his head almost as low as a katobleps. 'I, uh ... used to play this stupid card game when I was younger. Mythomagic. The katobleps was one of the monster cards.'

Frank blinked. 'I played Mythomagic. I never saw that card.'

'It was in the Africa.n.u.s Extreme expansion deck.'

'Oh.'

Their host cleared his throat. 'Are you two done, ah, geeking out, as they say?'

'Right, sorry,' Nico muttered. 'Anyway, katoblepones have poison breath and a poison gaze. I thought they only lived in Africa.'

The man in denim shrugged. 'That's their native land. They were accidentally imported to Venice hundreds of years ago. You've heard of Saint Mark?'

Frank wanted to scream with frustration. He didn't see how any of this was relevant, but, if their host could heal Hazel, Frank decided maybe it would be best not to make him angry. 'Saints? They're not part of Greek mythology.'

The man in denim chuckled. 'No, but Saint Mark is the patron saint of this city. He died in Egypt, oh, a long time ago. When the Venetians became powerful ... well, the relics of saints were a big tourist attraction back in the Middle Ages. The Venetians decided to steal Saint Mark's remains and bring them to their big church of San Marco. They smuggled out his body in a barrel of pickled pig parts.'

'That's ... disgusting,' Frank said.

'Yes,' the man agreed with a smile. 'The point is you can't do something like that and not have consequences. The Venetians unintentionally smuggled something else out of Egypt the katoblepones. They came here aboard that ship and have been breeding like rats ever since. They love the magical poison roots that grow here swampy, foul-smelling plants that creep up from the ca.n.a.ls. It makes their breath even more poisonous! Usually the monsters ignore mortals, but demiG.o.ds ... especially demiG.o.ds who get in their way '

'Got it,' Frank snapped. 'Can you cure her?'

The man shrugged. 'Possibly.'

'Possibly?' Frank had to use all his willpower not to throttle the guy.

He put his hand under Hazel's nose. He couldn't feel her breath. 'Nico, please tell me she's doing that death-trance thing, like you did in the bronze jar.'

Nico grimaced. 'I don't know if Hazel can do that. Her dad is technically Pluto, not Hades, so '

'Hades!' cried their host. He backed away, staring at Nico with distaste. 'So that's what I smell. Children of the Underworld? If I'd known that, I would never have let you in!'

Frank rose. 'Hazel's a good person. You promised you would help her!'

'I did not promise.'

Nico drew his sword. 'She's my sister,' he growled. 'I don't know who you are, but if you can cure her you have to, or so help me by the River Styx '

'Oh, blah, blah, blah!' The man waved his hand. Suddenly where Nico di Angelo had been standing was a potted plant about five feet tall, with drooping green leaves, tufts of silk and half a dozen ripe yellow ears of corn.

'There,' the man huffed, wagging his finger at the corn plant. 'Children of Hades can't order me around! You should talk less and listen more. Now at least you have ears.'

Frank stumbled against the bed. 'What did you why ?'

The man raised an eyebrow. Frank made a squeaky noise that wasn't very courageous. He'd been so focused on Hazel, he'd forgotten what Leo had told them about the guy they were looking for. 'You're a G.o.d,' he remembered.

'Triptolemus.' The man bowed. 'My friends call me Trip, so don't call me that. And if you're another child of Hades '

'Mars!' Frank said quickly. 'Child of Mars!'

Triptolemus sniffed. 'Well ... not much better. But perhaps you deserve to be something better than a corn plant. Sorghum? Sorghum is very nice.'

'Wait!' Frank pleaded. 'We're here on a friendly mission. We brought a gift.' Very slowly, he reached into his backpack and brought out the leather-bound book. 'This belongs to you?'

'My almanac!' Triptolemus grinned and seized the book. He thumbed through the pages and started bouncing on the b.a.l.l.s of his feet. 'Oh, this is fabulous! Where did you find it?'

'Um, Bologna. There were these ' Frank remembered that he wasn't supposed to mention the dwarfs 'terrible monsters. We risked our lives, but we knew this was important to you. So could you maybe, you know, turn Nico back to normal and heal Hazel?'

'Hmm?' Trip looked up from his book. He'd been happily reciting lines to himself something about turnip-planting schedules. Frank wished that Ella the harpy were here. She would get along great with this guy.

'Oh, heal them?' Triptolemus clucked disapprovingly. 'I'm grateful for the book, of course. I can definitely let you go free, son of Mars. But I have a long-standing problem with Hades. After all, I owe my G.o.dly powers to Demeter!'

Frank racked his brain, but it was hard with the voices screaming in his head and the katobleps poison making him dizzy.

'Uh, Demeter,' he said, 'the plant G.o.ddess. She she didn't like Hades because ...' Suddenly he recalled an old story he'd heard at Camp Jupiter. 'Her daughter, Proserpine '

'Persephone,' Trip corrected. 'I prefer the Greek, if you don't mind.'

Kill him! Mars screamed.

I love this guy! Ares yelled back. Kill him anyway!

Frank decided not to take offence. He didn't want to get turned into a sorghum plant. 'Okay. Hades kidnapped Persephone.'

'Exactly!' Trip said.

'So ... Persephone was a friend of yours?'

Trip snorted. 'I was just a mortal prince back then. Persephone wouldn't have noticed me. But when her mother, Demeter, went searching for her, scouring the whole earth, not many people would help her. Hecate lit her way at night with her torches. And I ... well, when Demeter came to my part of Greece, I gave her a place to stay. I comforted her, gave her a meal, and offered my a.s.sistance. I didn't know she was a G.o.ddess at the time, but my good deed paid off. Later, Demeter rewarded me by making me a G.o.d of farming!'

'Wow,' Frank said. 'Farming. Congratulations.'

'I know! Pretty awesome, right? Anyway, Demeter never got along with Hades. So naturally, you know, I have to side with my patron G.o.ddess. Children of Hades forget it! In fact, one of them this Scythian king named Lynkos? When I tried to teach his countrymen about farming, he killed my right python!'

'Your ... right python?'

Trip marched over to his winged chariot and hopped in. He pulled a lever, and the wings began to flap. The spotted python on the left wheel opened his eyes. He started to writhe, coiling around the axle like a spring. The chariot whirred into motion, but the right wheel stayed in place, so Triptolemus spun in circles, the chariot beating its wings and bouncing up and down like a defective merry-go-round.

'You see?' he said as he spun. 'No good! Ever since I lost my right python, I haven't been able to spread the word about farming at least not in person. Now I have to resort to giving online courses.'

'What?' As soon as he said it, Frank was sorry he'd asked.