Later, he couldn't remember the details clearly. He sliced through monsters until he was ankle-deep in yellow dust. Whenever he got overwhelmed and the clouds of gas began to choke him, he changed shape became an elephant, a dragon, a lion and each transformation seemed to clear his lungs, giving him a fresh burst of energy. His shape-shifting became so fluid, he could start an attack in human form with his sword and finish as a lion, raking his claws across a katobleps's snout.

The monsters kicked with their hooves. They breathed noxious gas and glared straight at Frank with their poisonous eyes. He should have died. He should have been trampled. But somehow he stayed on his feet, unharmed, and unleashed a hurricane of violence.

He didn't feel any sort of pleasure in this, but he didn't hesitate, either. He stabbed one monster and beheaded another. He turned into a dragon and bit a katobleps in half, then changed into an elephant and trampled three at once under his feet. His vision was still tinted red, and he realized his eyes weren't playing tricks on him. He was actually glowing surrounded by a rosy aura.

He didn't understand why, but he kept fighting until there was only one monster left.

Frank faced it with his sword drawn. He was out of breath, sweaty and caked in monster dust, but he was unharmed.

The katobleps snarled. It must not have been the smartest monster. Despite the fact that several hundred of its brethren had just died, it did not back down.

'Mars!' Frank yelled. 'I've proven myself. Now I need a snake!'

Frank doubted anyone had ever shouted those words before. It was kind of a weird request. He got no answer from the skies. For once, the voices in his head were silent.

The katobleps lost patience. It launched itself at Frank and left him no choice. He slashed upward. As soon as his blade hit the monster, the katobleps disappeared in a flash of blood-red light. When Frank's vision cleared, a mottled brown Burmese python was coiled at his feet.

'Well done,' said a familiar voice.

Standing a few feet away was his dad, Mars, wearing a red beret and olive fatigues with the insignia of the Italian Special Forces, an a.s.sault rifle slung over his shoulder. His face was hard and angular, his eyes covered with dark sungla.s.ses.

'Father,' Frank managed.

He couldn't believe what he'd just done. The terror started to catch up with him. He felt like sobbing, but he guessed that would not be a good idea in front of Mars.

'It's natural to feel fear.' The war G.o.d's voice was surprisingly warm, full of pride. 'All great warriors are afraid. Only the stupid and the delusional are not. But you faced your fear, my son. You did what you had to do, like Horatius. This was your bridge, and you defended it.'

'I ' Frank wasn't sure what to say. 'I ... I just needed a snake.'

A tiny smile tugged at Mars's mouth. 'Yes. And now you have one. Your bravery has united my forms, Greek and Roman, if only for a moment. Go. Save your friends. But hear me, Frank. Your greatest test is yet to come. When you face the armies of Gaia at Epirus, your leadership '

Suddenly the G.o.d doubled over, clutching his head. His form flickered. His fatigues turned into a toga, then a biker's jacket and jeans. His rifle changed into a sword and then a rocket launcher.

'Agony!' Mars bellowed. 'Go! Hurry!'

Frank didn't ask questions. Despite his exhaustion, he turned into a giant eagle, s.n.a.t.c.hed up the python in his ma.s.sive claws and launched himself into the air.

When he glanced back, a miniature mushroom cloud erupted from the middle of the bridge, rings of fire washing outwards, and a pair of voices Mars and Ares screamed, 'Noooo!'

Frank wasn't sure what had just happened, but he had no time to think about it. He flew over the city now completely empty of monsters and headed for the house of Triptolemus.

'You found one!' the farmer G.o.d exclaimed.

Frank ignored him. He stormed into La Casa Nera, dragging the python by its tail like a very strange Santa Claus bag, and dropped it next to the bed.

He knelt at Hazel's side.

She was still alive green and shivering, barely breathing, but alive. As for Nico, he was still a corn plant.

'Heal them,' Frank said. 'Now.'

Triptolemus crossed his arms. 'How do I know the snake will work?'

Frank gritted his teeth. Since the explosion on the bridge, the voices of the war G.o.d had gone silent in his head, but he still felt their combined anger churning inside him. He felt physically different, too. Had Triptolemus got shorter?

'The snake is a gift from Mars,' Frank growled. 'It will work.'

As if on cue, the Burmese python slithered over to the chariot and wrapped itself around the right wheel. The other snake woke up. The two serpents checked each other out, touching noses, then turned their wheels in unison. The chariot inched forward, its wings flapping.

'You see?' Frank said. 'Now, heal my friends!'

Triptolemus tapped his chin. 'Well, thank you for the snake, but I'm not sure I like your tone, demiG.o.d. Perhaps I'll turn you into '

Frank was faster. He lunged at Trip and slammed him into the wall, his fingers locked around the G.o.d's throat.

'Think about your next words,' Frank warned, deadly calm. 'Or, instead of beating my sword into a ploughshare, I will beat it into your head.'

Triptolemus gulped. 'You know ... I think I'll heal your friends.'

'Swear it on the River Styx.'

'I swear it on the River Styx.'

Frank released him. Triptolemus touched his throat, as if making sure it was still there. He gave Frank a nervous smile, edged around him and scurried off to the front room. 'Just just gathering herbs!'

Frank watched as the G.o.d picked leaves and roots and crushed them in a mortar. He rolled a pill-sized ball of green goop and jogged to Hazel's side. He placed the gunk ball under Hazel's tongue.

Instantly, she shuddered and sat up, coughing. Her eyes flew open. The greenish tint in her skin disappeared.

She looked around, bewildered, until she saw Frank. 'What ?'

Frank tackled her in a hug. 'You're going to be fine,' he said fiercely. 'Everything is fine.'

'But ...' Hazel gripped his shoulders and stared at him in amazement. 'Frank, what happened to you?'

'To me?' He stood, suddenly self-conscious. 'I don't ...'

He looked down and realized what she meant. Triptolemus hadn't got shorter. Frank was taller. His gut had shrunk. His chest seemed bulkier.

Frank had had growth spurts before. Once he'd woken up two centimetres taller than when he'd gone to sleep. But this was nuts. It was as if some of the dragon and lion had stayed with him when he'd turned back to human.

'Uh ... I don't ... Maybe I can fix it.'

Hazel laughed with delight. 'Why? You look amazing!'

'I I do?'

'I mean, you were handsome before! But you look older, and taller, and so distinguished '

Triptolemus heaved a dramatic sigh. 'Yes, obviously some sort of blessing from Mars. Congratulations, blah, blah, blah. Now, if we're done here ...?'

Frank glared at him. 'We're not done. Heal Nico.'

The farm G.o.d rolled his eyes. He pointed at the corn plant, and BAM! Nico di Angelo appeared in an explosion of corn silk.

Nico looked around in a panic. 'I I had the weirdest nightmare about popcorn.' He frowned at Frank. 'Why are you taller?'

'Everything's fine,' Frank promised. 'Triptolemus was about to tell us how to survive the House of Hades. Weren't you, Trip?'

The farm G.o.d raised his eyes to the ceiling, like, Why me, Demeter?

'Fine,' Trip said. 'When you arrive at Epirus, you will be offered a chalice to drink from.'

'Offered by whom?' Nico asked.

'Doesn't matter,' Trip snapped. 'Just know that it is filled with deadly poison.'

Hazel shuddered. 'So you're saying that we shouldn't drink it.'

'No!' Trip said. 'You must drink it, or you'll never be able to make it through the temple. The poison connects you to the world of the dead, lets you pa.s.s into the lower levels. The secret to surviving is ' his eyes twinkled 'barley.'

Frank stared at him. 'Barley.'

'In the front room, take some of my special barley. Make it into little cakes. Eat these before you step into the House of Hades. The barley will absorb the worst of the poison, so it will affect you, but not kill you.'

'That's it?' Nico demanded. 'Hecate sent us halfway across Italy so you could tell us to eat barley?'

'Good luck!' Triptolemus sprinted across the room and hopped in his chariot. 'And, Frank Zhang, I forgive you! You've got s.p.u.n.k. If you ever change your mind, my offer is open. I'd love to see you get a degree in farming!'

'Yeah,' Frank muttered. 'Thanks.'

The G.o.d pulled a lever on his chariot. The snake-wheels turned. The wings flapped. At the back of the room, the garage doors rolled open.

'Oh, to be mobile again!' Trip cried. 'So many ignorant lands in need of my knowledge. I will teach them the glories of tilling, irrigation, fertilizing!' The chariot lifted off and zipped out of the house, Triptolemus shouting to the sky, 'Away, my serpents! Away!'

'That,' Hazel said, 'was very strange.'

'The glories of fertilizing.' Nico brushed some corn silk off his shoulder. 'Can we get out of here now?'

Hazel put her hand on Frank's shoulder. 'Are you okay, really? You bartered for our lives. What did Triptolemus make you do?'

Frank tried to hold it together. He scolded himself for feeling so weak. He could face an army of monsters, but as soon as Hazel showed him kindness he wanted to break down and cry. 'Those cow monsters ... the katoblepones that poisoned you ... I had to destroy them.'

'That was brave,' Nico said. 'There must have been, what, six or seven left in that herd.'

'No.' Frank cleared his throat. 'All of them. I killed all of them in the city.'

Nico and Hazel stared at him in stunned silence. Frank was afraid they might doubt him, or start to laugh. How many monsters had he killed on that bridge two hundred? Three hundred?

But he saw in their eyes that they believed him. They were children of the Underworld. Maybe they could sense the death and carnage he'd unleashed.

Hazel kissed his cheek. She had to stand on her tiptoes to do it now. Her eyes were incredibly sad, as if she realized something had changed in Frank something much more important than the physical growth spurt.

Frank knew it too. He would never be the same. He just wasn't sure if that was a good thing.

'Well,' Nico said, breaking the tension, 'does anyone know what barley looks like?'

XXI.

ANNABETH.

ANNABETH DECIDED THE MONSTERS wouldn't kill her. Neither would the poisonous atmosphere, nor the treacherous landscape with its pits, cliffs and jagged rocks.

Nope. Most likely she would die from an overload of weirdness that would make her brain explode.

First, she and Percy had had to drink fire to stay alive. Then they were attacked by a gaggle of vampires, led by a cheerleader Annabeth had killed two years ago. Finally, they were rescued by a t.i.tan janitor named Bob who had Einstein hair, silver eyes and wicked broom skills.

Sure. Why not?

They followed Bob through the wasteland, tracing the route of the Phlegethon as they approached the storm front of darkness. Every so often they stopped to drink firewater, which kept them alive, but Annabeth wasn't happy about it. Her throat felt like she was constantly gargling with battery acid.

Her only comfort was Percy. Every so often he would glance over and smile, or squeeze her hand. He had to be just as scared and miserable as she was, and she loved him for trying to make her feel better.

'Bob knows what he's doing,' Percy promised.

'You have interesting friends,' Annabeth murmured.

'Bob is interesting!' The t.i.tan turned and grinned. 'Yes, thank you!'

The big guy had good ears. Annabeth would have to remember that.

'So, Bob ...' She tried to sound casual and friendly, which wasn't easy with a throat scorched by firewater. 'How did you get to Tartarus?'

'I jumped,' he said, like it was obvious.

'You jumped into Tartarus,' she said, 'because Percy said your name?'