aven was finishing off a hurried lunch when Jarvis appeared and handed him a letter. He reached for it eagerly, anxious for news of Gabriela. He looked at the stamp in the hope of seeing King Friedrich Wilhelm, but was disappointed.

‘From Albany Street,’ the butler said pointedly.

He opened it hurriedly and immediately recognised that the hand was not Sarah’s. The signature confirmed that it had indeed come from Archie, asking Raven to bring him a stock bottle of chloroform at his earliest convenience. Raven wondered why the man had not asked his wife to pick up a bottle from Duncan and Flockhart’s. It was equidistant and she was well enough known at the pharmacists’ premises as not to be denied. Then it struck him that perhaps Archie did not wish her to know how much of it he was getting through.

Raven suppressed a sigh and started upstairs to retrieve a bottle from the sideboard in Dr Simpson’s office. It being the afternoon, the professor was at the university giving a lecture. If Raven recalled correctly, at this point in the syllabus it would be about fibroid tumours of the uterus. The professor continued to be one of the more popular lecturers at the university. He was an engaging speaker whose skilful use of anecdote and personal experience illumined what in another’s hands would be deathly dull. Raven recalled how inspired he had been by Simpson’s words and his manner when he sat before him as a student, and then how proud he had been in assisting at those same lectures as his apprentice. He had dutifully collated and carried the copious notes for each talk, never to see the man refer to them.

These thoughts served to emphasise how the professor was lacking his usual sparkle. Raven felt again a degree of shame that he had been slow to come to his defence, and grateful that Sarah had been so insistent. He was impatient to tell Dr Simpson about how they intended to exonerate him, but was wary of being premature in his announcements. He did not have the hard proof he required yet, but once he did, the denials and objections of the likes of Miller and Duncan would surely be swept aside as their peers digested the significance of Raven’s discovery.

He strode into Simpson’s study and was startled to find it occupied, Mr Quinton seated at the professor’s desk. Quinton looked up from the document before him, peering over his spectacles like some feather-bare raptor.

Raven recovered from his fright and made for the sideboard, bending to retrieve the bottle he required.

‘What are you doing?’ Quinton asked, with a tone that implied he had the right to know.

‘I might ask you the same question,’ Raven replied.

‘I am attempting to bring order to this chaos,’ Quinton said, gesturing to the storm of papers that was Simpson’s desk. ‘And you?’