It was wishful thinking that the Phlegethon would work like that. Then again, Tartarus would eventually kill him anyway, wouldn’t it? Monsters he could fight. But thirst … that would be slower, more painful and just as lethal.

Nico knelt. Hesitantly, he touched the surface of the ‘water’.

It wasfreezing. He yanked his fingers back, only to discover that his skin was still very much intact and very muchnoton fire. He waited a few seconds, certain that his pain receptors would kick in, or that he would combust.

But no. His hand ached from the cold, but there were no burn marks.

He removed his jacket and set it aside.

Here goes nothing, he thought.

Then his thirst took over.

He cupped his hands, dipped them in the icy flames and brought the water to his lips.

The effect was instantaneous. He choked and gagged, the fire raging down his throat and into his belly. He clutched at his stomach. His vision doubled, and he was certain this was the end. This was how he’d go out: curled up next to the River of Fire. From which he’d DRUNK like a fool.

But the pain began to fade. Nico lay there, gasping, and his exhaustion began to slip away. The soles of his feet no longer ached. His head feltclearer.

Nico sat up, and the burning … was all gone. Not only that, he no longer felt thirsty.

Had just a small sip of the Phlegethon done all that?

He decided not to question it any further. It was a win-win. He wasn’t dead, and he’d just figured out that he could survive if he drank from aliteralriver of fire. Nico grabbed his leather jacket and slipped it on, then stood up and brushed himself off.

The forest awaited him. As did the Doors of Death.

So the son of Hades kept going.

Days passed.

Or maybe it was hours. Or weeks. Or months, for that matter. Nemesis had warned him about her mother, who only came out during the day, but Nico had no sense of when one day might be passing into another down here. The light did not change. The weather was always hellish with an 80 percent chance of noxious clouds and scattered monsters. Tartarus simply pressed down on his spirit as Nico moved deeper and deeper, following the Phlegethon as it cut through the forest.

He went as long as he could between sips from the river. He had no idea if there were any long-term effects from drinking fire, but the river water seemed to heal any exhaustion or pain that Nico was experiencing. It didnothelp him with the mental ramifications of being in Tartarus. He missed the sun. And solid food. He missed Camp Half-Blood and the satyrs and Chiron’s stern fatherly voice, and even the way Mr D whined and complained as if he were beingmurdered continuously day in and day out. Nico missed the other demigods, like Percy and Annabeth and Jason, even if he wasn’t sure they missed him.

It didn’t help that the forest – thick with a smelly, sulphurous fog – was so thoroughly unlike any woods Nico had ever been in. The trees contorted around one another, and the branches seemed to bend ever so slowly in Nico’s direction, even though the trunks looked completely dead, rotten on the inside and falling apart. Nico could not see above the treetops because of the impossible fog, but he heard creatures flying above, whooping and shrieking. Bushes like tumbleweeds – but with much sharper thorns and burrs – clogged the forest floor, and Nico often had to use his sword to clear his way, which sent small lizard-rat creatures scurrying away from him.

The glowing eyes were back, too: always floating in the shadows at the edge of his vision, always watching him. He wondered why the owners of those eyes never approached or attacked. What were they waiting for? There were far more of them than there was of him. Nico stayed on constant guard, awaiting the inevitable, and the anticipation was perhaps worse than if he’d actually been attacked.

He was so focused on the eyes that he barely realized that he’d reached the far side of the forest. The fog suddenly lifted, and he was met with an unending and impenetrable wall of darkness. It stretched in every direction, as far as he could see. Even the River Phlegethon made a sharp left turn and wended off to the north, as if it didn’t want to deal with that darkness. Nico stopped and stared, uncertain of what to do. How could Tartarus justendlike that?

The ground below him continued for a few metres, so he took a step. Then another.

Then a narrow rift appeared in the darkness: a vertical fissurethat revealed a dirt pathway sloping down gently until it ended at a black stone archway, not unlike the masonry on the parapets of Erebos. It looked like …

A doorway.

Was itthedoorway?

The idea was appealing. What if the Doors of Death weren’t some huge gates guarded by countless monsters from Gaia’s army but just a simple arch hidden in the middle of nowhere?

Nico didn’t want to get too excited, yet it was hard to contain himself. He moved forward onto the dirt path. He tested it with a single footstep. It did not give way. The walls of darkness on either side did not close in on him.

Okay, he thought. Feels real enough.

Another step. Another. He was halfway across when he felt compelled to look behind himself for a second. The Phlegethon cast an eerie glow over the trees. Nico was afraid to leave the only source of water that had been keeping him alive, but … he had to. He felt sure this was where he was supposed to be.

Near the end of the path, he noticed something about the archway that he couldn’t have seen from a distance.