What McLevy could not know was that they might not need the rope to finish Sarah, but certainly Raven could think of no greater horror than for her to survive only to be executed alongside him for a crime they did not commit.

He took some solace from knowing that someone capable was caring for her right now. To his shame, when Martha volunteered to stay with her while he went to Warnock’s Close, it had crossed his mind that she was not as sought-after as her sister, and he had wondered if this reflected upon her abilities as a nurse. He could almost laugh. She was less sought-after than the sister who murdered her patients. Could there be a greater indictment of the value of reputation in this town?

Actually, yes. The word of a thief and forger could be beyond question because he had gone to Oxford and was ostensibly respectable. Quinton had sealed Raven’s fate in order to protect himself and conceal the truth of his deeds from Simpson. And a man as caring as Simpson could be falsely accused of killing a patient, purely to satisfy the slighted honour of lesser men.

Raven now knew what had really happened to Mrs Johnstone, but Mary Dempster was dead, and he did not know what would become of her confession. Soutar could be using the pages as firelighters, for all he knew.

Still the snoring thundered from somewhere in the gloom. He wished for the same oblivion. Raven cradled his head in his hands, elbows on his thighs. He felt like all had been for naught. All was lost.

‘When do we get something to drink in here?’ someone shouted, though there did not appear to be a police officer present to answer.

‘This piss pot is full,’ a voice replied. ‘You can drink that.’

As he heard this, it occurred to Raven how thirsty he was, and how long it had been since he last drank anything. This called to mind an image of the empty glasses and the gin bottle on the floor in Warnock’s Close.

Two glasses.

His mind raced, suddenly alert. All in that room had not been as it appeared.

Raven began to reassess his memories of what he had seen, things that in his alarm and excitement might not have been apparent.

She had gone to the room to write her confession, and then to kill herself. In what vessel then had she brought the poison that she drank? Was it the gin bottle? If so, where was the bag or box in which she had brought it, along with the paper, the ink, the pen, the food, the glasses?

The two glasses.

Someone else had been in there and left again. Someone else had arranged the scene.