Arrived at his house, he insisted that I should enter for a "night-cap," it being then just past three o'clock. Therefore, reluctantly, I accompanied him within. In his study a tantalus-stand and glasses were upon the table. He had thrown off his overcoat, and was about to pour me out some whisky, when the telephone bell suddenly rang. He put down the glass, and, walking to the instrument, answered the summons. "Hulloa? Yes?" he said. Then, as he listened intently, his face blanched. He spoke some quick words in German, which, unfortunately, I could not follow. They seemed like instructions. Again he listened, but suddenly whatever he heard so appalled him that the receiver dropped from his thin, nerveless fingers, and with a low, hoarse cry he staggered across to his big grandfather chair, near which I was standing, and sank into it, rigid, staring, open-mouthed. If ever guilt were written upon a man's face, it assuredly was written upon that of Kershaw Kirk at that moment. CHAPTER FIVE. CERTAIN SUSPICIONS STRENGTHENED. To Mabel, my wife, I said nothing. In the circumstances, I deemed silence golden. Kirk's attitude at the telephone had filled me with suspicion. During the hours I spent in bed before the dawn I lay thinking. The problem was utterly inexplicable, the more so now that the dead man's daughter was also dead. I was convinced, as I lay there in the darkness, that there was something very suspicious in the fact that Kirk, who seemed to rule the household, would not allow the police to have any knowledge of what had occurred. Indeed, my own position was somewhat unenviable, for, being aware that a murder had been committed, was I not legally bound to give information? Was I not liable to prosecution if I failed to do so? The mystery surrounding Kershaw Kirk had increased rather than diminished in that final quarter of an hour I had spent with him as he had sat staring straight into the fire, uttering scarce a word. What had been told him over the telephone had caused an entire change in his manner. Previously he had been dictatorial and defiant. He was now cringing, crushed, terror-stricken. The grim scenes I had witnessed surged through my brain. The mystery of it all had gripped my senses. Carefully I analysed each event, trying to discern some light as to its cause and motive. But I was not a professional detective. This was the first time I had found myself mixed up in a crime by which human life had been lost. That the death of Professor Greer was no ordinary crime of violence I had quickly recognised. There was some subtle motive both in the crime itself and in the supposed presence of the Professor in Edinburgh, whereas in reality he was already lying dead in his own laboratory. Those instructions to his daughter, which seemed to have been written after his departure from King's Cross, also formed an enigma in themselves. The dead man had actually sought the assistance of his worst enemy!