Colin glanced at his watch. "Oh, very well," he said curtly. "I sha'n't have time to attend to the man properly, but if I find it's a matter for surgical treatment I'll give you a note to the hospital. Just wait here and I'll be with you in a minute." He stepped back into the consulting room, and, crossing to the opposite door, summoned Martha Jane. "When Miss Nancy comes in," he said, "you might tell her that I've been called out on an urgent case. I'm only going as far as the bottom of Flood Lane, so I shall be back by six." He thrust one or two articles which might be needed into his bag, and, hurrying out again into the hall, unhooked his hat and coat. "What sort of injury is it?" he asked, as the front door closed behind them. "A broken leg or something of that kind?" His companion, who was slightly ahead of him, pushed open the small iron gate and turned to the left in the direction of the river. "No," he answered slowly, "'e ain't broke nothing--leastways, not as I knows of. The pain's inside of 'im, so 'e says. Twisted 'is guts, I reckon, from the way 'e's carryin' on." He relapsed into silence, and, checking his pace a few yards farther on, led the way down a dark and narrow alley. They emerged on to a desolate strip of waste land, where stray piles of brick and other refuse were dotted about forlornly under the light of a solitary street lamp. Exactly opposite them were the partly demolished remains of a large warehouse, with two crazy and tumble-down houses still standing alongside. Behind these, half a mile wide, ran the dark and sluggish current of the Thames. Colin's guide pointed across toward the dilapidated dwellings. "That's the 'ouse," he observed, "the end one o' them two. You want to step careful, doctor; there's a number o' bad places abaht 'ere." He set forward again, picking his way deliberately between the heaps of débris and the numerous pools of dirty water which infested the whole district. Colin followed close behind him, and after several minutes of this unpleasant progress they came out on to a muddy and deserted roadway which ran parallel with the river. Colin glanced back over the route they had come. "A nice open situation," he remarked, "but I should think that the people who lived here were rather apt to break their necks." "It's an orkard spot to get to in the dark," admitted his companion. "You'll be all right though, doctor. I'll see yer back meself as far as Flood Lane." He crossed the road and advanced toward the houses, one of which appeared to be uninhabited. A dim light was burning on the ground floor of the second, and, mounting the broken step, he rapped twice on the door with his knuckles. After some delay it was opened by a gaunt, haggard-looking woman, who held up the candle she was carrying and peered suspiciously into the darkness. She evidently recognized the visitor, for without inquiring his business she stepped back silently against the wall.