Zena had said it was curious the tragedy should happen while Dr. Hawes was away, and the professor declared it was this remark which had led him to believe that the dead woman was Mrs. Harrison and not Mrs. Jardine. On this supposition the attitude of Martha Wakeling was understandable. She might naturally wish to protect her mistress, and she was the only person who could help her in the deception. The fact that I had given her a reason to suppose that I suspected the nephew would show her the necessity of warning him, and at the same time she would attempt to throw all the suspicion on Mrs. Harrison, who was past suffering. This was Quarles's theory, and he had found the fact to support it in the handwriting of the store's order. CHAPTER VII THE DEATH-TRAP IN THE TUDOR ROOM I had not been to Chelsea for some weeks--indeed, I had not been in town, business having kept me in the country--and I returned to find a letter from Quarles which had been waiting for me for three days. Several cases were in my hands just then--affairs of no great difficulty nor any particular interest--and only in one case had I had any worry. This trouble was due, not so much to the case itself as to the fact that it had brought me in contact with another detective named Baines, who would persist in treating me as a rival. He was as irritating as Quarles himself could be on occasion, and was entirely without the professor's genius. To be candid, I may admit Baines had some excuse. Circumstances brought me into the affair at the eleventh hour, and he was afraid I should reap where he had planted. It was a strange business from first to last, and one I am never likely to forget. A man, riding across an open piece of country near Aylesbury early one morning, came upon a motor cyclist lying near his machine on the roadside. The machine had been reduced to scrap-iron. The man, who was dressed in overalls, seemed to have been killed outright by a blow on the head. Since the man still wore his goggles, and there was no sign of a struggle, Baines argued, and reasonably, I think, that death was not the result of foul play. That he had been run into by a motor car, and that the people in the car had either not stopped to see what damage was done, or, having seen it, feared to give information, was perhaps giving too loose a rein to imagination. However, this was Baines's idea; and he had succeeded in hearing of a car with only one man in it which had been driven through Aylesbury at a furious pace on the night when a second and similar tragedy occurred, this time near Saffron Walden.