The Clock in the Hatbox — Anthony Gilbert

Richard Arnold, a juror in the case, was certain that beautiful Viola Ross could not have murdered her husband, Teddy. He set about his own investigations before Viola faced a second trial. Knowing Viola had quarrelled frequently with her husband over her stepson, Harry Ross, Arnold concentrated his search for new evidence on Harry. Arnold discovered that Harry had had both provocation and opportunity and, unbearable as the suspicion was to Arnold, Harry could have been infatuated with his exquisite young stepmother. The ingenuity of the plot places this story high on the list of classic mysteries.