‘Run along,’ Raven muttered. He would likely encounter him again soon enough, or one of his colleagues would. It only remained to be seen whether it was in a hospital bed or in the mortuary.

He put the knife away but reckoned it might not be the last time he would have to defend himself before he left this neighbourhood.

Raven stepped into a stairwell on the right where the smell of urine was at least a change from faeces in the gutter. As he ascended, he heard retching behind one door, the sounds of congress behind another: male grunts and exaggerated yelps of female pleasure. He identified a professional performance, intended to hasten the conclusion.

The address he had been given was on the sixth floor. Simpson’s words were a mockery in his head as the climb tested his thighs, but the sixth floor wasn’t even the top of this ramshackle construction. It might have been once, as might the fifth or fourth, but more storeys had been added over the years, hence the buckling of the walls below.

He knocked on the appointed door, immediately hearing some movement in response to the thumps, but the source sounded lighter than a human on the move. It was not the tread of footsteps, but a sudden scuttling: birds perhaps, or cats. He thought again of the oddness of Mary’s request, which had rightly unsettled Martha.

The door was locked but it was a rotten, ancient-looking thing. It took very little effort to force it, the wood crumbling away from the lock, which clattered to the floor.

The smell hit him as soon as he opened the door, but it was not the only thing to come rushing his way. The scuttling sound had been at least two dozen rats, initially disturbed by his thumping and now startled by the sight of his presence. They were scurrying to get away, but he was standing before the only exit. He had to kick and stamp as they flowed towards him, though not all of them were skittish in the face of human interruption.

A hardy few were proving themselves reluctant to give up their feast.

She was lying with her back to him before an overturned chair, from which she must have tumbled. She was wearing the same style of dress he had seen draped over her bed: dark blue with white braiding on the cuffs. Raven stepped around to the other side of the body, causing the last of the vermin to scatter. He did not recall much about her face from their brief encounter at Broughton Street, but that would have made no difference. The rats had nibbled away at the exposed areas first.