Cooper allowed himself a smile as he entered the darkened mill. The times Fry expressed concern for his welfare were so rare that they were worth collecting and treasuring for posterity.

He and Kotsev made their way slowly through the shopping floor. Although it was open-plan, there were far too many places to hide – counters and display units, racks of winter coats and free-standing shelves full of pottery. It would take dozens of people to search this place properly.

Without the presence of people, the dominant smell was the scent of polish rising from the wooden floors, as if they were walking through a low-lying mist. Cooper’s torchlight reflected off mirrors everywhere, dazzling him with sudden bursts of glare. Time and again, he caught a movement across the other side of the floor and swung his Maglite towards it, only to see himself or Georgi staring back from a full-length mirror, pale and wide-eyed like ghosts.

When they came to the central stairs, Kotsev gestured upwards, and Cooper nodded. He watched until Georgi reached the top of the first flight, then he moved on.

And it was better on his own, without the distraction of someone else’s footsteps behind him, another person’s breathing in his ear, or that continual jump and flutter on the edge of his vision. Now, he could concentrate on the natural sounds of the building, he could listen for the subtle intrusions into the silence, the surreptitious movement in the darkness.

When he felt the floorboards shift and groan under his feet, Cooper knew he was near the wooden steps that led down to the museum at river level. Standing perfectly still, he held his breath and listened. The faint creak of boards came from below him, somewhere near the bottom of the stairs.

The stairs led down to two doors, one opening into the spinning room and the other into the weaving shed. A doubling machine and some of the looms had been running last time he was here. The rattle of their bobbins and leather drive belts had seemed normal background noises then. Without them, the place was much too quiet, the long lines of wooden spindles dead and still, like rows of broken fingers.

His torchlight gleamed on white and pale blue walls, glared off red fire buckets, picked out the rainbow colours of the cotton on the bobbins. The weaving sheds had pitched roofs that were half glass to provide natural light for the weavers. Tonight, though, the glass only reflected his torch beam and the sporadic glint of machinery from the sheds beneath.