Suddenly another theory leaped into the detective’s mind, but after careful thought he felt he must reject it. If Vanderkemp were guilty, the whole of these mysterious happenings would be cleared up. Harrington was under a deep debt of gratitude to his uncle, and appeared attached to him. Whether Miss Duke shared, or was endeavouring to share, his feelings, French did not know, but it was certainly possible. Suppose he and Miss Duke, driving home from the East End, had seen Vanderkemp at the end of Hatton Garden. Suppose, moreover, something in the man’s appearance had attracted their attention, something furtive or evil, something unlike his usual expression. This, coupled with the fact that the traveller was supposed to be in Amsterdam, might easily have impelled Harrington to stop the cab to have a word with his uncle. But by the time he had reached the pavement, Vanderkemp had disappeared. The incident would have been dismissed by both as trivial, until next morning at breakfast, when Miss Duke learned of the murder, its significance would become apparent. She might not believe the traveller guilty, but she would recognise that the circumstances required some explanation. Immediately the paramount importance of communicating with Harrington would appear, lest he might incautiously mention that he had seen his uncle virtually on the scene of the murder. She would instantly telephone in the hope of catching her lover before he left his rooms. She could not give her message over the telephone, so she would arrange the meeting. She would instruct Harrington to return to her as soon as possible, so as to hear what had taken place at the office. He would therefore call in the afternoon, and at the interview they would decide that in the uncertainty of the situation, the wedding should be postponed. The supposed flight of Vanderkemp would confirm their suspicions, and would account for the perturbed state of mind which both exhibited. The theory was so fascinating that next day French once more interviewed Harrington and Miss Duke and put the question directly to them, Had they seen Vanderkemp? But both denied having done so, and baffled and irritated, he wrathfully watched another promising clue petering out before him. He had the two young people shadowed, and spent a considerable time in investigating their past life, but without result. So the days began to draw out into weeks, and the solution of the mystery seemed as far off as ever. CHAPTER IX MRS. ROOT OF PITTSBURG ONE morning about six weeks after the murder in Hatton Garden, Inspector French was summoned to the presence of his chief. “Look here, French,” he was greeted, “you’ve been at that Gething case long enough. I can’t have any more time wasted on it. What are you doing now?”