The two passed through the shop into the road. As they crossed it, Mr. Ludgrove uttered an exclamation of surprise. “Why, the door of my shop is open!” he said. “I must have forgotten to shut it in my haste when Ted Copperdock came over for me.” “Let’s hope no inquisitive visitor has been in to have a look round while we’ve been over the way,” replied Whyland. Mr. Ludgrove smiled. “He will have found very little of value to reward him if he has,” he said. “No, I’m not afraid of burglars. In any case, it’s a very old-fashioned lock which anyone could force without any difficulty.” They had reached the door by now, and Mr. Ludgrove pushed it open. “Come along, Inspector, we’ll go into the back room,” he said, leading the way. At the door of the inner room he paused, and switched on the light. At a first glance, the room appeared to be exactly as he had left it to answer Ted’s urgent summons. Then suddenly he clutched Whyland’s arm, and pointed straight in front of him with a shaking finger. On the mantelpiece, propped conspicuously against the clock so that it could not fail to attract attention, was a white bone counter, upon which the figure VII had been carefully traced. Part II The Criminal Chapter XIII Enter Dr. Priestley That eccentric scientist, Dr. Priestley, sat in his study on the Monday morning following the death of Mr. Copperdock, busily engaged in sorting out a mass of untidy-looking papers. Most of them he tore up and placed in the waste-paper basket by his side; a few he glanced at and put aside. The April sun lit up the room with a pale radiance, lending an air of Spring even to this dignified but rather gloomy house in Westbourne Terrace. Dr. Priestley was thus engaged when the door opened and his secretary, Harold Merefield, came into the room. There was an air of heaviness about both men, the old and the young, as though the Spring had not yet touched them, and Winter held them still in its grip. One might have guessed that some absorbing work had monopolized their energies, leaving them no leisure for anything but the utmost concentration. And one would have guessed right. For the last six months Dr. Priestley had been engaged upon the writing of a book which was to enhance his already brilliant reputation. Its title was _Some Aspects of Modern Thought_, and in it Dr. Priestley had, with his usual incontrovertible logic, shattered the majority of the pet theories of orthodox science. It was, as the reviews were to say, a brilliant achievement, all the more entertaining from the vein of biting sarcasm which ran through it.