When James Orr woke up, a little later than usual, he had the sense that there was something not quite right, some indefinable shift in the normal order of things, but it was not until he bumped into his wife on the landing – James had been sleeping in the spare room for several weeks – that he had a clue as to what it might be.

‘Oh!’ said Sarah Orr, and put her hand to her mouth in genuine alarm.

James continued to the bathroom and there, in the mirror, he saw the cause of her dismay – and it did not seem unreasonable.

The left side of James’s face had collapsed, a balloon with the air gone out of it, a melted waxwork. The cheek was hollow and the skin hung in a bulge over the side of his jaw, a grotesque one-sided jowl. The side of his mouth had fallen, too, the pale line of his lips angling sharply downwards. Where the bottom of his eyelid had pulled down, the full white of the eye was exposed, as well as its veiny roots. The skin itself was different. Yellowed, bloodless and a little shiny.

James tried to smile. Only the right side responded. The right eye narrowed, the skin creased into folds, the corner of the mouth hoisted itself upwards and pulled his lips back over his teeth. The left side remained slumped, unmoved. The effect, a forced and crooked grin, the teeth bared on one side, was appalling.