A LARGE ORANGE cat, a male as its owner insisted that only males possessed the requisite temperament to share his lodgings, was curled on the grand piano, swishing its ringed tail slowly back and forth like a metronome. Its master, a tall man in early middle age, sat comfortably in his favourite armchair, imagining an invisible pianist playing a melody synchronized with the motion of the cat’s tail. He gazed contentedly around the book-lined study, with its worn Persian carpet and eclectic works of art on the panelled walls and exotic objects from India and the West Indies. After a moment he lowered his eyes to the thick volume in his lap, titled Principles of Toxicology, consulted the index and located the entry he was seeking. With down-turned mouth, he grimly read the description of the properties of the powerful poison and its recommended uses, in extremely small doses, for the treatment of a host of human and veterinary maladies. Snapping the volume shut and putting it aside, he rose, walked to the coal scuttle, and used the tongs to place another lump on the grate, radiating warmth. With his back to the fire, he listened to the sound of the door in the hall and observed as a large man, wearing a heavy coat with fur collar, gloves, and astrakhan hat entered the study.

‘Good evening, Cameron,’ said the visitor, removing his hat and tossing it on a chair.

‘Good evening, Clifton,’ replied Duncan Cameron in a faint Scottish burr.

His visitor, obviously very much at home, stripped off his gloves and coat, which he folded over the back of the chair. Reaching for a crystal decanter on a trolley, he poured an inch of brandy in a tumbler and said, ‘Wretched night out.’

Cameron straightened his waistcoat and gazed at James Clifton, a heavy-set man of similar age with dark sideburns and moustache in contrast to Cameron’s clean-shaven face. ‘You may pour me a glass,’ Cameron said pleasantly.

Handing Cameron his brandy, Clifton said, ‘Cheers,’ and raised his glass. ‘Who was the lady,’ he asked, ‘leaving in that elaborate coach as I was paying off the hansom?’

‘A certain Lady Cranbrook,’ said Cameron, swirling his brandy before taking a sip.

‘Oh, really? Not the same Cranbrook in the newspapers …’ said Clifton, his bushy eyebrows upraised.

‘Precisely. The poor man’s mother. Obviously, much distressed.’

Clifton took a step toward the door and removed a cavalry sabre from an umbrella stand. He briefly studied its fine tempered blade and tested its sharpness on his thumb. ‘And so,’ he said, ‘did you agree to assist…?’

‘Without hesitation.’ Cameron sipped his brandy and smiled. ‘The lady’s prepared to pay a handsome fee.’ He walked over to take the sabre from his friend and then suddenly lunged and thrust its tip into one of the pillows on the sofa. ‘And I imagine,’ he concluded, tossing the sabre back to Clifton, ‘the case will prove to be a formidable, and exceptionally intriguing, challenge.’