He lay on his side, facing away from her, arms bound behind his back. She couldn’t tell if he was conscious, or even alive. But the distorted smear of crimson in the dirt under his head suggested they had shared the same treatment.

Hawkins’ muscles screamed as she tried to sit up, protective emotion spilling over as she stared at him. But her nervous system ignited, agonizing shockwaves bursting in her head and upper limbs, forcing her back. She sank down, panting.

Then it made sense. The sense of motion she had experienced moments earlier had been the attacker dragging her, half-conscious, into the tower. And the reason she couldn’t move was because her arms and legs were bound, the same as Mike’s.

A scuffing sound from the rear corner dragged her attention away. Without thinking, she moved her head in response. Immediately, footsteps moved towards her, and then a face appeared, filling her view. Her vision was still blurred, reducing its features to indefinite smears, but there was no question.

It was Joseph White.

‘Detective?’ His voice echoed, although it wasn’t clear if that was just in her head. ‘Can you hear me?’

She stared up at him. Clearly, he could see she was conscious, but his question implied that her state of mind was more difficult to gauge. Should she answer, or fake disorientation? Neither strategy held an obvious advantage.

‘You’ve killed five people,’ she croaked.

White didn’t answer directly. Instead, he made a noise that sounded like mild approval. ‘I expect you’re feeling an amount of distress. I did give you quite a whack, after all.’ He rose and moved away, revealing black jeans and a black jacket, talking over his shoulder. ‘Regrettably your friend’s still unconscious, but we’ll give him a bit longer, see if he comes round.’

‘Why are you doing this?’ Hawkins asked as he crouched over Mike.

White was silent for a few seconds. ‘I’m not sure you’d understand.’

‘Try me.’ Every word sent pain shooting outwards from the backs of her eyes, but her vision was sharpening. She could now make out detail on the various alcoves and recesses in the opposite wall, the chaotic patchwork of ancient mortar and stone, mere blotches until a moment ago.

The fact White had assaulted two police officers and wasn’t denying his crimes meant she probably wasn’t supposed to be leaving here alive, but if she could keep him talking long enough to determine his motivation, perhaps she could find a way out of this.

‘Are you familiar with Darwin’s theory on natural selection?’ White rolled Mike on to his back and tapped the side of his face, apparently trying to rouse him. ‘Where two parties of equal strength compete for limited resources, the individual most suited to the environment survives.’

‘I know it …’ she said. ‘What does that have to do with killing members of other spiritual groups?’