"About two weeks ago I was ordered by these people to place a certain sum in that oak tree. Naturally, I ignored the demand and notified the police. Since then I have taken every precaution to protect myself against attack. Unable to get at me, it seems obvious that these contemptible wretches have reached me through my son. That, I believe, is a new angle, and shows the extremes to which these people are prepared to go." "When did this happen, Mr. Melville?" asked Forrester. "About a half-hour ago, I should say, I saw my son pass into the conservatory with this young lady," and Mr. Melville turned toward Mary Sturtevant for the first time. Forrester also turned and looked at the girl. She met his gaze steadily. "Shortly after I came here," she explained, "my next dancing partner entered and claimed me. I left young Mr. Melville sitting near that open window over there." Forrester gave no outward indication of the shock he had received. He clearly remembered that after young Melville’s dance the next three dances were his. It was during the first of these, the one she had intimated belonged to someone else, that he had missed the girl. He knew, therefore, that she had lied deliberately, placing it squarely up to him to protect her. "Protect her from what?" thought Forrester. "What was this frightful new development in the mystery?" "I decided I wanted a smoke," continued Mr. Melville, "and so came into the conservatory. A moment later I found my son on the floor beneath that open window where Miss Sturtevant says she left him. My doctor was among the guests and I summoned him at once—but too late, it seems." "Any other facts?" asked Forrester, and received another shock when the doctor handed him a small piece of filmy white fabric. "I found this beside the body," said the doctor. And added, as Forrester took it, "Note the peculiar odor." Forrester lifted the fabric to his nose. Instantly he recognized the same pungent, drug-like smell which he had noticed the night he was attacked with the death mask. Examining the filmy bit of cloth, Forrester saw that it was a part of a lady’s handkerchief which had been torn in half. In one corner the letter "S" was embroidered. Crumpling the handkerchief in his hand, Forrester pushed it into his waistcoat pocket. "I believe I can make use of this," he said. CHAPTER XVII—AT THE DOORSTEP