Paul Sturgess is engaged to Grace Van Austin. At a party at their Newport home, Grace flirts with Howard Esterbrook leading to a fight between the two men. Later that night, a servant witnesses Paul, with a revolver entering Esterbrook's room. The servant follows, sees a hand emerging from a window curtain, stab Esterbrook then vanish mysteriously. Paul is arrested based on circumstantial evidence. Six months later, a woman known as "The Woman of Mystery" is shot during a raid while trying to assist the police. Moved by hearing about Paul's denied pardon and impending execution, the "Woman of Mystery" reveals information to the detective leading the raid. This revelation leads to a call to the Sing Sing Warden just in time to halt Paul's electrocution.