‘What was that?’ Silvius looked around. Through the gloom in front of them appeared the outline of a beast. He gripped his sword, and realised that it would be as effective against this thing as a pin.

It was vast, and it was angry. It reared upwards, higher than the ferryman, and it had many heads at the ends of long necks, some like snakes, some like wolves, some like lions. All of the heads were spitting and foaming with rage.

‘What is it?’ asked Silvius, trembling.

‘One of Python’s children …’ The Sibyl’s fingers tightened their grip on her lion’s mane.

With a growl, a wolf’s head came rushing towards Silvius. Panicked, he jumped out of the way, the head missing him by a knuckle’s breadth. Tisamenos had bashed away a lion’s head, but it was already springing back. And Elissa was running from a snake, fangs exposed. There was no escape from those jaws, those huge, terrible appetites.

Snapping back, the wolf head faced Silvius once more, and gritting his teeth, he stabbed it in the cheek. His sword came out bloody and steaming, but the wolf’s head simply shook itself from side to side. And then it paused, looking down at Silvius, as if considering how exactly it was going to destroy him.

It was about to strike. Whichever way he turned, he would not escape it. Desperate, Silvius pointed the sword upwards, hoping that as it came down he would be able to get its throat.

The wolf’s head gathered its strength. It had yellow eyes, its mouth open revealing sharp fangs that dripped with slobber.

A beam of light, hurtling through the darkness, struck the wolf on its skull, and it whimpered and withdrew. Silvius saw the Sibyl with a glowing golden staff in her hand, the aura expanding and surrounding him in a shield of brightness.

Fangs dripping with venom, the many-headed monster shrieked an unearthly cry from all its heads.

‘This light will keep us safe,’ shouted the Sibyl. ‘Keep close to me.’

Roaring with frustration, the monster flung several of its heads towards them. Silvius tensed.

But the light protected them, and the beast gave one last howl of rage as they rushed away.

Once they’d gone some distance, they slowed to a walk. The golden light made a circle around them, flickering and bright.

Outside its reach, Silvius sensed movement. Once he thought his name was being called, and he turned around and saw something like a person, but wispy and insubstantial. Tisamenos was looking about from side to side, whilst Elissa had her hands over her ears. Only the Sibyl walked calmly, straight and unerring, and the lion kept up the rear.

Again Silvius thought he heard his name. His hairs were standing on end, his arms covered in goose pimples.

‘What is it?’ he asked.

‘It’s the Underworld,’ answered the Sibyl. ‘Do not listen. It will drive you mad.’