Men often talked about a woman’s intuition. Ostensibly it sounded complimentary and yet its intention was usually patronising and dismissive: a term for irrational flights of fancy that these silly creatures would occasionally dream up from nowhere. Sarah understood the true nature of what they were describing. It was not irrational, and nor was it a mystical sixth sense resultant of a uniquely feminine sensitivity. It was a simple, practical consequence of observation. When you put them in a room, women paid attention to the subtle signs people were sending, while the men concerned themselves only with the impression they were making.

Raven thought he was looking for a new disease. Sarah thought that something more sinister was afoot.

If Mary Dempster had made her own sister afraid, she had made other people afraid before her. Her deeds would have left a trail, and Sarah knew where she might pick it up.

FORTY-TWO

here was frost beneath Raven’s feet as he walked along Princes Street, a glistening unwelcome harbinger of the harsh months ahead. Raven was prompted to think back to the unprecedented heat he had endured during his summer in Berlin, but was grateful not to be there now. He had heard stories about the winter in that city and had no desire to witness it first-hand.

A few yards ahead he saw a smartly dressed gentleman emerge from one of the hotels, and recognised him as Dr Alison, Professor of Medicine at the university, and, more pertinently for Raven’s purposes, the author of an influential pamphlet on the spread of infectious disease.

Fortune was smiling upon Raven, and not before time. It was a chance encounter, but one which Raven decided to put to good use. He approached the man and tipped his hat.

‘Professor Alison, I am Dr Raven, assistant to Dr Simpson.’

It came as a relief to see Professor Alison’s eyes widen in positive affirmation of the name. Given the bad blood emanating from everything that Simpson had become caught up in, it was easy to forget how many of his peers in the city held him in the highest regard. And to Raven’s further delight, it seemed Simpson’s was not the only name familiar to him.

‘Yes, of course. Will, isn’t it? I recall we dined together at Queen Street when you were studying under James as his apprentice.’

‘How kind of you to remember. And what a stroke of luck that I have run into you today. If you have the time, perhaps you would be good enough to bestow upon me the benefit of your wisdom? I have recently had to contend with several cases of what I believe might be a new form of transmissible infection.’

Professor Alison looked intrigued.

‘I have an idle moment right now. Perhaps we might retire somewhere out of the cold and avail ourselves of tea, or something stronger, while we discuss it?’