She retreated to the van, wondering if she could disable it in some way, to prevent the bastards making a quick getaway; perhaps get under its front end and rip some wiring out, or maybe just let the air from its tyres, anything that would maroon them here while she nipped off and called for back-up – though she still wasn’t prepared to do that until she knew where that wretched Tessa Payne was. She returned to the internal door, ear cocked, again hearing nothing. For several seconds she was torn. On one hand, she ought to keep investigating for the sake of her colleague, even if that meant penetrating deeper into the building. But on the other, it went against the cardinal rule of street-policing, that you never entered a suspicious premises alone.

And then she heard the moan.

Incredulous, she leaned against the internal door.

Another moan sounded. It came distinctly from what sounded like an adult female.

Lucy yanked the door open.

A brick stairway overhung with cobwebs led down into a basement area. There was no light on the stairs, but the door at the bottom stood half open, and a weak, reddish glow shone past it. She hurried down, half tripping on the cable, which descended alongside her.

Another moan sounded, more protracted this time, laden with pain.

She reached the bottom, opened the door and found herself facing a bare corridor with numerous doorways leading off it. Unlike the subterranean passage in the Torgau house, it was dank and filthy, the dull, reddish glow filling it. When she heard the fourth moan, it was louder and led her straight to a turn on the left.

Around it, lying splayed on the passage floor, head resting in a semi-congealed crimson pool, was Tessa Payne.

‘Christ!’ Lucy slid to her knees alongside her.

The young detective mumbled something inaudible, her eyes not completely closed, their lids fluttering. Lucy flicked her Maglite on and saw that the casualty’s crinkly hair was clotted with freshly shed blood.

‘Lucy …’ Payne muttered.

‘Lie still, don’t try to move.’ Lucy laid her torch on the floor alongside them, then dug the last pair of disposable gloves from her pocket, and pulled them on, before carefully working her way along Payne’s scalp, foraging gently through the lush but sticky locks.

‘Tried to … call you back. But, your mobile …’

‘Yeah, my mobile’s knackered,’ Lucy said, distracted. ‘I told you that. What the hell, Tessa … who did this?’

‘Din’ … see them.’ Payne’s voice became a whimper as Lucy probed the wounded flesh, searching for signs of a fracture. ‘They came … from behind.’

‘Tessa, what are you doing here?’

‘You said … said something … about … nuns.’

‘And?’

‘Couple of days back, saw … saw van … dark-blue …’