Scudamore Lane, Sloping down riverwards from just behind the Monument, lies at night in the shadow of two black and monstrous walls which loom high above the glimmer of the scattered gas-lamps. The foot-paths are narrow, and the causeway is paved with rounded cobblestones so that the endless drays roar along it like so many breaking waves. A few old-fashioned houses lie scattered among the business premises, and in one of these— half-way down on the left-hand side—Dr Horace Selby conducts his large practice. It is a singular street for so big a man, but a specialist who has an European reputation can afford to live where he likes. In his particular branch, too, patients do not always regard seclusion as a disadvantage.

It was only ten o’clock. The dull roar of the traffic which converged all day upon London Bridge had died away now to a mere confused murmur. It was raining heavily, and the gas shone dimly through the streaked and dripping glass, throwing little yellow circles upon the glistening cobblestones. The air was full of the sounds of the rain, the thin swish of its fall, the heavier drip from the eaves, and the swirl and gurgle down the two steep gutters and through the sewer grating. There was only one figure in the whole length of Scudamore Lane. It was that of a man, and it stood outside the door of Dr Horace Selby.

He had just rung and was waiting for an answer. The fanlight beat full upon the gleaming shoulders of his waterproof and upon his upturned features. It was a wan, sensitive, clear-cut face, with some subtle, nameless peculiarity in its expression—something of the startled horse in the white-rimmed eye, something, too, of the helpless child in the drawn cheek and the weakening of the lower lip. The man-servant knew the stranger as a patient at a bare glance at those frightened eyes. Such a look had been seen at that door before.

‘Is the doctor in?’

The man hesitated.

‘He has had a few friends to dinner, sir. He does not like to be disturbed outside his usual hours, sir.’