They emerged on to a tier of prison cells that circled a wide, empty space, and the volume of the world suddenly twisted up to 11. Convicts cheered, raged, cursed at her, shouted a thousand threats that competed against each other in their race to be heard. She glanced upwards. It was almost dizzying. Tier after tier of hatred and anger and barely contained violence. Skulduggery wrapped an arm round her waist and they floated over the railing and across the gap to the wide, flat disc that hovered above a crackling lake of energy.

They touched down on the dais. Three metal Xs, skilfully welded and attached to hydraulic arms, stood waiting. She didn’t know what the curved metal plates were for, but, judging by the clasps on display, Valkyrie guessed that those Xs were reserved for her and the two other people on this platform who were wearing shackles. She didn’t recognise the older men, but they looked terrified. Memphis, resplendent in a red jacket and black shirt, gripped the arm of one of them and Razzia, clad in her usual tuxedo, made sure the other stayed put. Nero was too busy holding his head to even glance her way, and Smoke sat on the ground amid all those fallen scythes, frantically chewing leaves and clutching his leg.

Lethe was examining a metal tripod that had been set up near a table. No, not a table – more like a mortuary slab. Upon that slab were two wooden boxes. The bigger one was plain, without any ornamentation. The smaller was carved with intricate symbols. That was the one containing the heart; Valkyrie would have bet her life on it, if her life had been hers to bet. She wondered if she’d be able to lunge for the box and toss it into the lake of energy before anyone stopped her, but Skulduggery’s fingers tightened ever so slightly on her arm.

“Let’s not, shall we?” he said softly.

Lethe looked up. “Finally,” he said. “We are ready to proceed. Where is the good doctor?”

Melior appeared on the tier. He looked exhausted, and wouldn’t meet Valkyrie’s eyes. He peered down at the lake of energy below.

“Careful now,” Lethe called.

Melior took a running jump on to the dais. He stumbled slightly as he landed, and Razzia cheered. Ignoring her, he hauled three thick, transparent hoses out of a large sack. He dropped the hoses between the Xs and the tripod, and walked up to Valkyrie. He didn’t say anything, just raised his hand to her face. It started to glow, the warmth overcoming her pain, and when he took his hand away her lips were healed and her jaw didn’t ache.

“Hey,” Smoke said, getting up and hobbling over. “Do me. Fix my leg.”

“And my head,” said Nero. “I think I have concussion.”

“I can’t,” said Melior. “I need my strength for the resurrection.”