Fiancés Georg and Magda and their assistant Erik perform in a vaudeville act combining ventriloquism and hypnotism. Erik, jealously in love with Magda, kills Georg and frames Chris, an errand boy and petty thief, for t...展开he crime. Sought by the police, Chris goes into hiding and tries to blackmail Erik, but Erik kills him. Erik also tries to kill Carmen, Chris's sister, when she arrives looking for her brother; but Pablo, a policeman, foils him. Magda eventually frightens Erik into confessing to the murders by tormenting him with Georg's ventriloquist dummy Grog and tape recordings of Grog's laughter.