"Lord Wisbeach thought that they were trying to steal my nephew's explosive. Perhaps you have read in the papers that my nephew, Willie Partridge, has completed an explosive which is more powerful than any at present known. His father--you have heard of him, of course--Dwight Partridge." Mr. Sturgis nodded. "His father was working on it at the time of his death, and Willie has gone on with his experiments where he left off. To-day at lunch he showed us a test-tube full of the explosive. He put it in my husband's safe in the library. Lord Wisbeach is convinced that these scoundrels are trying to steal this, but I cannot help feeling that this is another of those attempts to kidnap my son Ogden. What do you think?" "It is impossible to say at this stage of the proceedings. All we can tell is that there is some plot going on. You refused, of course, to allow Mitchell to come back to the house?" "Yes. You think that was wise?" "Undoubtedly. If his absence did not handicap them, they would not be so anxious to have him on the spot." "What shall we do?" "You wish me to undertake the case?" "Of course." Mr. Sturgis frowned thoughtfully. "It would be useless for me to come here myself. By bad luck the man who pretends to be your nephew has seen me. If I were to come to stay here, he would suspect something. He would be on his guard." He pondered with closed eyes. "Miss Trimble," he exclaimed. "I beg your pardon." "You want Miss Trimble. She is the smartest worker in my office. This is precisely the type of case she could handle to perfection." "A woman?" said Mrs. Pett doubtfully. "A woman in a thousand," said Mr. Sturgis. "A woman in a million." "But physically would a woman be--?" "Miss Trimble knows more about jiu-jitsu than the Japanese professor who taught her. At one time she was a Strong Woman in small-time vaudeville. She is an expert revolver-shot. I am not worrying about Miss Trimble's capacity to do the work. I am only wondering in what capacity it would be best for her to enter the house. Have you a vacancy for a parlour-maid?" "I could make one." "Do so at once. Miss Trimble is at her best as a parlour-maid. She handled the Marling divorce case in that capacity. Have you a telephone in the room?" Mrs. Pett opened the stuffed owl. The detective got in touch with his office.