Conspiracy

Conspiracy (1931) starring Bessie Love, Ned Sparks, Hugh Trevor
Margaret Holt has been secretly helping her crusading D.A. brother get information on crime boss "Schemer" Marko. When the mobster confronts the brave girl, she accidentally kills him in self-defense. Looking for a place to hide, she stumbles upon the mansion of Winthrop Clavering, an amateur criminologist. Margaret becomes the man's stenographer, but soon realizes that he is close to solving the mystery of Marko's murder. Margaret must prove her innocence before Clavering turns her over to the authorities.