The shortest of director Michael Powell's surviving films, Rynox is based upon a novel by Philip MacDonald, one of the most popular mystery novelists of the time. "Rynox" is the name of the company headed by the wealthy F.X. Benedik, a businessman whose life has been threatened by a mysterious and violent stranger by the name of Boswell Marsh, who apparently holds a grudge against Benedik. When Benedik is found murdered, Marsh becomes the prime suspect and Benedik's son, Tony, turns his attention to both running the company and finding his father's killer. Tony eventually solves the mystery, along the way discovering that things are not always the way they seem. Rynox was remade in 1937 as Who Killed John Savage?