The black stone wasmoving.

Not shifting as a whole, but the arch appeared to be made of millions of tiny … well, he didn’t know what he was looking at. Particles of dust? Quicksand? He reached out to touch it, then jerked his hand away.

No, he thought.Don’t do that. Something is wrong.

Maybe he wasn’t at the Doors of Death after all. He turned again, looking wistfully back up the trail. Should he drink once more of the river? Maybe rest a while and think about this? The forest didn’t seem quite so creepy now.

The voice he heard forced his hand. It came from the rift at the top of the trail – an indistinct grumbling, getting closer, and definitely headed in Nico’s direction. Whatever it was, Nico estimated it was only seconds from appearing, seeing him and blocking his only exit.

With no other option, he darted through the archway, ducking to one side behind the nearest cover he could find: a tall tree with bark as black as night. Beyond, in the gloom, was an area that looked like an overgrown garden.

The voice got louder. Nico hid behind his tree just as something emerged from the archway. It was as if all of Nico’s blood instantly chilled, and when he slowly let out a breath he could see it condensing in the air.

‘Mother, she’s intolerable!’ said the voice. ‘Why do we have to listen to her?’

From deeper in the garden, another voice answered. It must have been Mother – and her tone was harsh and unforgiving.

‘I don’t know why my children are so disobedient,’ she said. ‘I created you. I gave you life, I gave you purpose, and what do I get in return?’

There was a terrible pause.

Then the first voice said, ‘Love and affection?’

‘Disrespect!’ shrieked Mother.

Nico moved slowly, turning his head until his right eye could just peek around the edge of the trunk. What he saw twisted his heart around his stomach.

Mother was enormous, at least three times the size of an adult human. She was swathed in smoke and ash that swirled around her like she was the eye of a hurricane. Her dress was the deepest black Nico had ever seen, glittering with the twinkles of entire galaxies.Her face was an indistinct mass of darkness, but her eyes burned with the fury of twin supernovas. She sat on a Stygian iron throne at the centre of a circle of black trees. Dark gravel paths wended between topiaries that looked like clouds of ink – every branch, leaf and flower competing to be the darkest thing in the garden. And in the distance, at the edge of Nico’s vision, rose some kind of onyx structure – perhaps a temple or a palace.

The other figure stood before Mother’s seat.

He was tall but more human size, with a dark skin tone and shoulder-length black braids. He wore a sweeping black coat that shimmered in mesmerizing patterns, making Nico’s eyes feel heavy. ‘No one is disrespecting you, Mother,’ he said, his tone guarded. ‘But Gaia is not our master. Why should we –?’

Mother unfurled a set of wings that stretched from one end of the tree circle to the other. Their leathery surface swirled with shadows. ‘Must you always disagree with me? After that last debacle with Kronos – which Itoldyou not to get involved in – you wouldn’t even be safe if I hadn’t let you stay here, Hypnos!’

Involuntarily, Nico grunted with surprise. The god Hypnos – who had put the entire island of Manhattan to sleep during Kronos’s assault on Olympus – apparently lived here now, in his mother’s basement?

Mother’s wings quivered, dripping liquid shadow from their spiny tips. ‘We are being watched,’ she said.

Her terrible eyes scanned the area where Nico was hiding. He jerked back and dropped to the ground, his heart racing.

He couldn’t get caught. Not this close to the end. And hehadto be close! He’d done as Nemesis told him and followed the River Phlegethon. Unless Nemesis had guided him into a trap …

Nico stayed as still as possible. The archway he’d entered wasonly a few steps away. Maybe, if he sprinted, he could get through it, back up the path and into the forest.

He never got to find out. Tendrils of smoke wrapped around him and abruptly lifted him into the air.

‘No!’ he cried as he was yanked backwards across the garden, then spun around to find himself face to face withher.

Up close, her visage wasn’t just dark and indistinct. Except for those piercing eyes, it was a churning void, a black hole devouring all light and matter. It was pure hopelessness made real.

‘Now, who areyou?’ Her supernova eyes seemed to be peeling back Nico’s soul layer by layer. Her swirling debris-cloud of darkness held him fast, but Nico didn’t struggle – he suddenly didn’twantto. He was paralysed.

‘I asked you a question,’ she said, and her voice hadgravity, as if it might pull the answers right out of his skull.

‘Mother, leave him alone,’ said Hypnos with a tired sigh. ‘It’s clear that he’s harmless.’

‘Harmless,’ Nico echoed, exhaustion spreading through his bones. ‘Definitely harmless.’