On the breezy shore of Lake Merced, under a November sky that was the colour of a Heermann’s gull, the greyest and darkest of all the gulls, Grant Melford was already waiting with his seconds and his doctor when Collis arrived. The wind whistled through the pale grasses and made soft thundery noises in Collis’s eardrums. He stood by the wheel of their hired carriage while Dan McReady gave the driver two dollars and asked him to wait. Fifty yards away, in his black cape and high silk hat, Grant Melford was watching him with a concentrated frown. Collis tried to smile, although he didn’t know why.

At length, the carriage was driven away out of earshot, and Collis walked across the grass, closely followed by Dan, to say good morning. Collis was wearing his grey morning suit, freshly-pressed that morning by the hotel valet, and Dan McReady was dressed in a coat of brown herringbone tweed and a round white hat. He was smoking a cigarette.

Grant Melford’s face was pale and oval as a sago pudding. He looked as if he hadn’t slept. One of his seconds was a serious young college type, tanned, with a small moustache, who squinted out of clear blue eyes like a slightly maniacal badminton umpire. The other must have been a servant, because he stood a few paces back, and his morning suit was half a size too large for him. He was big-nosed, with curly coppery hair, and he said nothing at all, though Collis heard him grunt.

Even further away, on a small grassy embankment, the doctor waited like a buzzard on a branch. He was elderly, with fraying white hair and tiny spectacles. His old brown leather bag lay at his feet. He coughed a great deal as Collis inclined his head towards Grant, and towards his seconds, and as Collis said, ‘Good morning, gentlemen. A dull day to die.’

Grant gave a jerky nod. ‘Good morning, Mr Edmonds. Allow me to introduce Mr Snaith and Mr O’Rourke. Our medical practitioner is Dr Mince.’

Collis gave each of them a sloping smile. The doctor, unexpectedly, waved.

Grant took a deep, unsteady breath. ‘I suppose you’re not prepared to withdraw your remark of last night?’ he asked Collis.

Collis glanced at Dan McReady, but all Dan McReady could do was give him a small shrug, as if to say, ‘It’s your duel — if you want to fight it, fight it.’ The young college type, Mr Snaith, waited with a large mahogany box in his arms, his finger on the catch, keeping the lid closed until he had heard Collis’s answer.