'Man, you gotta trust me.'

Frank's heart raced. Did he trust Leo? Well, sure ... with an engine. With a practical joke. But with his life?

He remembered the day they had got stuck in the underground workshop in Rome. Gaia had promised they would die in that room. Leo had promised he would get Hazel and Frank out of the trap. And he'd done it.

Now Leo spoke with the same kind of confidence.

'Okay.' Frank handed Leo the pouch. 'Try not to kill me.'

Leo's hand blazed. The pouch didn't blacken or burn.

Frank waited for something to go horribly wrong. He counted to twenty, but he was still alive. He felt as if a block of ice was melting just behind his sternum a frozen chunk of fear he'd got so used to he didn't even think about it until it was gone.

Leo extinguished his fire. He wriggled his eyebrows at Frank. 'Who's your best buddy?'

'Don't answer that,' Hazel said. 'But, Leo, that was amazing.'

'It was, wasn't it?' Leo agreed. 'So who wants to take this newly ultra-safe piece of firewood?'

'I'll keep it,' Frank said.

Hazel pursed her lips. She looked down, maybe so Frank wouldn't see the hurt in her eyes. She'd protected that firewood for him through a lot of hard battles. It was a sign of trust between them, a symbol of their relationship.

'Hazel, it's not about you,' Frank said, as gently as he could. 'I can't explain, but I I have a feeling I'm going to need to step up when we're in the House of Hades. I need to carry my own burden.'

Hazel's golden eyes were full of concern. 'I understand. I just ... I worry.'

Leo tossed Frank the pouch. Frank tied it around his belt. He felt strange carrying his fatal weakness so openly, after months of keeping it hidden.

'And, Leo,' he said, 'thanks.'

It seemed inadequate for the gift Leo had given him, but Leo grinned. 'What are genius friends for?'

'Hey, guys!' Piper called from the bow. 'Better get over here. You need to see this.'

They'd found the source of the dark lightning.

The Argo II hovered directly over the river. A few hundred metres away at the top of the nearest hill stood a cl.u.s.ter of ruins. They didn't look like much just some crumbling walls encircling the limestone sh.e.l.ls of a few buildings but, from somewhere within the ruins, tendrils of black ether curled into the sky, like a smoky squid peeking from its cave. As Frank watched, a bolt of dark energy ripped through the air, rocking the ship and sending a cold shockwave across the landscape.

'The Necromanteion,' Nico said. 'The House of Hades.'

Frank steadied himself at the rail. He supposed it was too late to suggest turning back. He was starting to feel nostalgic about the monsters he'd fought in Rome. Heck, chasing poison cows through Venice had been more appealing than this place.

Piper hugged her arms. 'I feel vulnerable floating up here like this. Couldn't we set down in the river?'

'I wouldn't,' Hazel said. 'That's the River Acheron.'

Jason squinted in the sunlight. 'I thought the Acheron was in the Underworld.'

'It is,' Hazel said. 'But its headwaters are in the mortal world. That river below us? Eventually it flows underground, straight into the realm of Pluto er, Hades. Landing a demiG.o.d ship on those waters '

'Yeah, let's stay up here,' Leo decided. 'I don't want any zombie water on my hull.'

Half a kilometre downstream, some fishing boats were puttering along. Frank guessed they didn't know or care about the history of this river. Must be nice, being a regular mortal.

Next to Frank, Nico di Angelo raised the sceptre of Diocletian. Its...o...b..glowed with purple light, as if in sympathy with the dark storm. Roman relic or not, the sceptre troubled Frank. If it really had the power to summon a legion of the dead ... well, Frank wasn't sure that was such a great idea.

Jason had once told him that the children of Mars had a similar ability. Supposedly, Frank could call on ghostly soldiers from the losing side of any war to serve him. He'd never had much luck with that power, probably because it freaked him out too much. He was worried he might become one of those ghosts if they lost this war eternally doomed to pay for his failures, a.s.suming there was anyone left to summon him.

'So, uh, Nico ...' Frank gestured at the sceptre. 'Have you learned to use that thing?'

'We'll find out.' Nico stared at the tendrils of darkness undulating from the ruins. 'I don't intend to try until I have to. The Doors of Death are already working overtime bringing in Gaia's monsters. Any more activity raising the dead and the Doors might shatter permanently, leaving a rip in the mortal world that can't be closed.'

Coach Hedge grunted. 'I hate rips in the world. Let's go bust some monster heads.'

Frank looked at the satyr's grim expression. Suddenly he had an idea. 'Coach, you should stay on board, cover us with the ballistae.'

Hedge frowned. 'Stay behind? Me? I'm your best soldier!'

'We might need air support,' Frank said. 'Like we did in Rome. You saved our braccae.'

He didn't add: Plus, I'd like you to get back to your wife and baby alive.

Hedge apparently got the message. His scowl relaxed. Relief showed in his eyes.

'Well ...' he grumbled, 'I suppose somebody's got to save your braccae.'

Jason clapped the coach on the shoulder. Then he gave Frank an appreciative nod. 'So that's settled. Everybody else let's get to the ruins. Time to crash Gaia's party.'

LXVI.

FRANK.

DESPITE THE MIDDAY HEAT and the raging storm of death energy, a group of tourists was climbing over the ruins. Fortunately there weren't many and they didn't give the demiG.o.ds a second look.

After the crowds in Rome, Frank had stopped worrying too much about getting noticed. If they could fly their warship into the Roman Colosseum with ballistae blazing and not even cause a traffic slowdown, he figured they could get away with anything.

Nico led the way. At the top of the hill, they climbed over an old retaining wall and down into an excavated trench. Finally they arrived at a stone doorway leading straight into the side of the hill. The death storm seemed to originate right above their heads. Looking up at the swirling tentacles of darkness, Frank felt like he was trapped at the bottom of a flushing toilet bowl. That really didn't calm his nerves.

Nico faced the group. 'From here, it gets tough.'

'Sweet,' Leo said. ''Cause so far I've totally been pulling my punches.'

Nico glared at him. 'We'll see how long you keep your sense of humour. Remember, this is where pilgrims came to commune with dead ancestors. Underground, you may see things that are hard to look at, or hear voices trying to lead you astray in the tunnels. Frank, do you have the barley cakes?'

'What?' Frank had been thinking about his grandmother and his mom, wondering if they might appear to him. For the first time in days, the voices of Ares and Mars had started to argue again in the back of Frank's mind, debating their favourite forms of violent death.

'I've got the cakes,' Hazel said. She pulled out the magical barley crackers they'd made from the grain Triptolemus had given them in Venice.

'Eat up,' Nico advised.

Frank chewed his cracker of death and tried not to gag. It reminded him of a cookie made with sawdust instead of sugar.

'Yum,' Piper said. Even the daughter of Aphrodite couldn't avoid making a face.

'Okay.' Nico choked down the last of his barley. 'That should protect us from the poison.'

'Poison?' Leo asked. 'Did I miss the poison? 'Cause I love poison.'

'Soon enough,' Nico promised. 'Just stick close together, and maybe we can avoid getting lost or going insane.'

On that happy note, Nico led them underground.

The tunnel spiralled gently downwards, the ceiling supported by white stone arches that reminded Frank of a whale's rib cage.

As they walked, Hazel ran her hands along the masonry. 'This wasn't part of a temple,' she whispered. 'This was ... the bas.e.m.e.nt for a manor house, built in later Greek times.'

Frank found it eerie how Hazel could tell so much about an underground place just by being there. He'd never known her to be mistaken.

'A manor house?' he asked. 'Please don't tell me we're in the wrong place.'

'The House of Hades is below us,' Nico a.s.sured him. 'But Hazel's right, these upper levels are much newer. When the archaeologists first excavated this site, they thought they'd found the Necromanteion. Then they realized the ruins were too recent, so they decided it was the wrong spot. They were right the first time. They just didn't dig deep enough.'

They turned a corner and stopped. In front of them, the tunnel ended in a huge block of stone.

'A cave-in?' Jason asked.

'A test,' Nico said. 'Hazel, would you do the honours?'

Hazel stepped forward. She placed her hand on the rock, and the entire boulder crumbled to dust.

The tunnel shuddered. Cracks spread across the ceiling. For a terrifying moment, Frank imagined they'd all be crushed under tons of earth a disappointing way to die, after all they'd been through. Then the rumbling stopped. The dust settled.

A set of stairs curved deeper into the earth, the barrelled ceiling held up by more repeating arches, closer together and carved from polished black stone. The descending arches made Frank feel dizzy, as if he were looking into an endlessly reflecting mirror. Painted on the walls were crude pictures of black cattle marching downwards.

'I really don't like cows,' Piper muttered.

'Agreed,' Frank said.

'Those are the cattle of Hades,' Nico said. 'It's just a symbol of '

'Look.' Frank pointed.

On the first step of the stairwell, a golden chalice gleamed. Frank was pretty sure it hadn't been there a moment before. The cup was full of dark-green liquid.

'Hooray,' Leo said halfheartedly. 'I suppose that's our poison.'

Nico picked up the chalice. 'We're standing at the ancient entrance of the Necromanteion. Odysseus came here, and dozens of other heroes, seeking advice from the dead.'

'Did the dead advise them to leave immediately?' Leo asked.

'I would be fine with that,' Piper admitted.

Nico drank from the chalice, then offered it to Jason. 'You asked me about trust, and taking a risk? Well, here you go, son of Jupiter. How much do you trust me?'

Frank wasn't sure what Nico was talking about, but Jason didn't hesitate. He took the cup and drank.

They pa.s.sed it around, each taking a sip of poison. As he waited his turn, Frank tried to keep his legs from shaking and his gut from churning. He wondered what his grandmother would say if she could see him.

Stupid, Fai Zhang! she would probably scold. If all your friends were drinking poison, would you do it too?

Frank went last. The taste of the green liquid reminded him of spoiled apple juice. He drained the chalice. It turned to smoke in his hands.

Nico nodded, apparently satisfied. 'Congratulations. a.s.suming the poison doesn't kill us, we should be able to find our way through the Necromanteion's first level.'

'Just the first level?' Piper asked.

Nico turned to Hazel and gestured at the stairs. 'After you, sister.'

In no time, Frank felt completely lost. The stairs split in three different directions. As soon as Hazel chose a path, the stairs split again. They wound their way through interconnecting tunnels and rough-hewn burial chambers that all looked the same the walls carved with dusty niches that might once have held bodies. The arches over the doors were painted with black cows, white poplar trees and owls.

'I thought the owl was Minerva's symbol,' Jason murmured.

'The screech owl is one of Hades's sacred animals,' Nico said. 'Its cry is a bad omen.'

'This way.' Hazel pointed to a doorway that looked the same as all the others. 'It's the only one that won't collapse on us.'

'Good choice, then,' Leo said.

Frank began to feel like he was leaving the world of the living. His skin tingled, and he wondered if it was a side effect of the poison. The pouch with his firewood seemed heavier on his belt. In the eerie glow of their magic weapons, his friends looked like flickering ghosts.

Cold air brushed against his face. In his mind, Ares and Mars had gone silent, but Frank thought he heard other voices whispering in the side corridors, beckoning him to veer off course, to come closer and listen to them speak.

Finally they reached an archway carved in the shape of human skulls or maybe they were human skulls embedded in the rock. In the purple light of Diocletian's sceptre, the hollow eye sockets seemed to blink.

Frank almost hit the ceiling when Hazel put a hand on his arm.