Aided by his trusty guide dog, blind investigator Duncan MacLain (Edward Arnold) takes on a case brought to him by old acquaintance Norma Lawry (Ann Harding). One of Norma's past lovers, veteran actor Paul Gerente (John Emery), has become involved with her much younger stepdaughter, Barbara (Donna Reed), and this situation gets more dramatic when the thespian is found dead. Soon the investigation extends beyond the Lawry ladies to include a sinister Nazi scheme.