For an hour they talked behind locked doors, and then Gurther came out, still showing his teeth in a mechanical smile, and went up the stairs two at a time. The half-witted Danish maid, passing the door of the doctor’s room, heard his gruff voice booming into the telephone, but since he spoke a language which, whilst it had some relation to her own, was subtly different, she could not have heard the instructions, admonitions, orders and suggestions which he fired in half a dozen different directions, even if she had heard him clearly. This done, Dr. Oberzohn returned to his book and a midday refreshment, spooning his lunch from a small cup at his side containing a few fluid ounces of dark red liquid. One half of his mind was pursuing his well-read philosophers; the other worked at feverish speed, conjecturing and guessing, forestalling and baffling the minds that were working against him. He played a game of mental chess, all the time seeking for a check, and when at last he had discovered one that was adequate, he put down his book and went out into his garden, strolling up and down inside the wire fence, stopping now and again to pick a flower from a weed, or pausing to examine a rain-filled pothole as though it were the star object in a prize landscape. He loved this ugly house, knew every brick of it, as a feudal lord might have known the castle he had built, the turret, the flat roof with its high parapet, that commanded a view of the canal bank on the one side and the railway arches left and right. They were railway arches which had a value to him. Most of them were blocked up, having been converted into lock-up garages and sheds, and through only a few could ingress be had. One, under which ran the muddy lane—why it was called Hangman’s Lane nobody knew; another that gave to some allotments on the edge of his property; and a third through which he also could see daylight, but which spanned no road at all. An express train roared past in a cloud of steam, and he scanned the viaduct with benignant interest. And then he performed his daily tour of inspection. Turning back into the house, he climbed the stairs to the third floor, opened a little door that revealed an extra flight of steps, and emerged on to the roof. At each corner was a square black shed, about the height of a man’s chest. The doors were heavily padlocked, and near by each was a stout black box, equally weatherproof. There were other things here: great, clumsy wall-plugs at regular intervals. Seeing them, it might be thought that Mr. Oberzohn contemplated a night when, in the exultation of achievement, he would illuminate his ungainly premises. But up till now that night had not arrived, and in truth the only light usable was one which at the moment was dismantled in the larger of the four sheds.