He moved down to the end of the corridor and pushed through into the stairwell. ‘I’m kind of in the middle of something, Dave.’

‘Excellent, excellent. Look, I’ve got you a profile for Agnes Garfield.’

‘That was quick.’

‘Had a head start. Do you want the highlights? Agnes’s psychological condition means it’s unlikely she’s operating alone, or in a dominant role. She’s a subservient fantasist, looking for someone to make her dreams come true. That coupled with the obsession with books like Witchfire means she’s trying to live a life that never existed in the first place. She’ll probably resort to self-harm when things don’t live up to her expectations.’

‘Subservient? Didn’t you see what she did to Anthony Chung? Far as we can tell, he’s the only dominant—’

‘No. She’d never do anything to hurt or disappoint him. It isn’t—’

‘She staked him out on the linoleum and tortured him to death, Dave. Doesn’t get more final than that.’

Silence came from the other end of the line.

‘Dave? ’

‘Then that idiot Marks is even more useless than I thought. His files clearly show she’s elevated Anthony Chung to the position of personal deity. There’s literally nothing he can do that she isn’t going to forgive or see as a test of her faith. Infidelity, violence, abnormal sexual behaviour. . .’

‘Well, he must’ve done something, because he’s lying in the morgue with. . .’ Logan frowned at the stained concrete beneath his feet. ‘Wait a minute: Marks’s files? ’

‘Have you read Witchfire? In it there are three primary forms of punishment doled out by the Fingermen: trial by fire, trial by blood, and trial by water. We’ve had the first two. She’s going to have a go at chucking someone in a river next, and if they don’t drown she’ll drag them back on shore and burn them.’

‘How did you get your hands on Dr Marks’s files? ’

‘Agnes started off pretending to be in Rowan’s world. It was a harmless fantasy, daydreaming she was someone special with a destiny and power, but she did it so often that it became habitual. The fantasy became real. She’s not play-acting any more, she genuinely thinks they’re witches and they’re evil and they need to be purged to save their souls.’ A deep breath. ‘And that’s where the problem starts: there’s a dichotomy at the heart of Agnes’s psyche and it’s eating her sense of self. In the book, Rowan’s a witch-finder that doesn’t believe in witches, but has to punish them. But Agnes doesn’t just believe in witches, she thinks she is one. She’s trapped between two diametric delusions.’

‘Dave!’