Barbara Thurston stood at the window of a large old-fashioned house, looking out into Connecticut Avenue. It was almost dark. An occasional light twinkled outside in the street, but the room in which Barbara was stationed was still shrouded in twilight. Suddenly she heard a curtain at the farther end of the drawing-room rustle faintly. Bab turned and saw a young man standing between the curtains, peering into the shadows with a pair of near-sighted eyes. Barbara started. The stranger had entered the room through a small study that adjoined it. He seemed totally unaware of any other presence, for he was whistling softly: "Kathleen Mavourneen."