 The corrupt Lord Ambrose D Arcy (Michael Gough) steals the life s work of the poor musical Professor Petry. (Herbert Lom). In an attempt to stop the printing of music with D Arcy s name on it, Petry breaks into the printing office and accidentally starts a fire, leaving him severely disfigured. Years later, Petry returns to terrorize a London opera house that is about to perform one of his stolen operas.