threw the rays of his electric torch over the door.

    "It doesn't seem to be," he remarked; "in fact, the door is ajar."

    Farrington gasped.

    "Ajar?" he repeated. T. B. stepped out into the well of the tiny courtyard. It was approached from the street by a flight of stone stairs.

    T. B. threw the circle of his lamp over the flagged yard. He saw something glittering and stooped to pick it up. The object was a tiny gold-capped bottle such as forms part of the paraphernalia in a woman's handbag.

    He lifted it to his nose and sniffed it.

    "That is it," he said.

    "What?" asked Mr. Farrington, suspiciously.

    "The scent I detected in your hall," replied T. B. "A peculiar scent, is it not?" He raised the bottle to his nose again. "Not your ward's by any chance?"

    Farrington shook his head vigorously.

    "Doris has never been in this area in her life," he said; "besides, she dislikes perfumes."

    T. B. slipped the bottle in his pocket.

    Further examination discovered no further clue as to the third person, and T. B. followed his host back to the study.

    "What do you make of it?" asked Mr. Farrington.

    T. B. did not answer immediately. He walked to the window and looked out. The little crowd which had been attracted by the shots and arrival of the police ambulance had melted away. The mist which had threatened all the evening had rolled into the square and the street lamps showed yellow through the dingy haze.

    "I think," he said, "that I have at last got on the track of Montague Fallock."

    Mr. Farrington looked at him with open mouth.

    "You don't mean that?" he asked incredulously.

    T. B. inclined his head.

    "The open door below—the visitor?" jerked the stout man, "you don't think Montague Fallock was in the house to-night?"

    T. B. nodded again, and there was a moment's silence.

    "He has been blackmailing me," said Mr. Farrington, thoughtfully, "but I don't think——"

    The detective turned up his coat collar preparatory to leaving.

    "I have a rather unpleasant job," he said. "I shall have to search those unfortunate men."

    Mr.