Discovered by Marston in the act of robbing the safe, Mann, the crook, shoots and slays him. The murderer escapes, carrying with him a casket containing jewels. So strongly do circumstances point to Lyda, Marston's daughter, as the slayer, that she is tried for the crime. Despite the evidence of the butler and other servants, who tell of a violent quarrel between Lyda and her father just prior to the shooting, the girl is acquitted.