He put one on, then passed the other over. Waiting until the historian had his in place before stepping off the walkway onto the one-foot-square patch of linoleum just inside the door marked with black-and-yellow tape as safe. Then from there straight back onto the first tray of the path set up in the kitchen.

It was a reasonably modern space, but completely empty. No pots, no pans, no toaster, no kettle, and no furniture, just the little drifts of fly carcases piled up by the skirting boards. The walls were a disturbing shade of rippling grey.

A ragged pentagram, about six-foot across, sat in the middle of the blue-and-cream linoleum. It was lumpen, spotted, as if it’d been made by melting black candle wax onto the floor, layered over with a series of concentric circles punctuated by incomprehensible words and squiggles. Like a demonic sheriff’s badge. The smears and pools of dried blood just added to the image.

Five holes pierced the linoleum, a couple of inches in from the pentagram’s points.

Alex paused on the threshold, rubbing his fingertips down the front of his jacket, as if that would keep them clean. He stared down at the gap in the walkway. ‘I thought we weren’t supposed to—’

‘They can’t lay the trays where the door goes, can they? ’

‘Ah, OK, yes, got you. . .’ He cleared his throat, then stepped inside. Clunked the door shut behind him.

The noise must have startled the flies, because the walls went from grey to magnolia as they buzzed into the rank air, bobbing and swirling like angry smoke. Alex froze. ‘I. . .’

‘Ignore them.’ The walkway detoured around the pentagram and headed further off into the house. Logan stopped at the top of the five-pointed star. ‘Well, you’re the witchcraft expert: is that what I think it is? ’

‘Ah, OK. . .’ A cough. ‘Do you have any gloves? ’

Logan handed him a pair, and the historian struggled them on over trembling fingers.

He hunkered down on the walkway, head moving from side to side. ‘It’s a magic circle.’

Pause. ‘I’m going to need slightly more than that.’

‘Ah, yes, of course. . .’ He puffed out a breath. ‘Right, this is basically a corruption of the circles described in The Key of Solomon. Going by strict Qabalistic belief, the pentagram shouldn’t be there, it’s wrong. It shouldn’t cross the outer circles either.’