Caught in a loveless marriage, Dr. John Winnington (Ronald Howard) can't stop himself from falling for his wife's (Mary Laura Wood) younger sister, Christine (Olga Edwardes). But when he suddenly becomes the prime suspect in his wife's tragic murder, John relies on his friend Eric (John Bentley) to clear his name. This classic murder mystery encourages viewers to evaluate all of the clues and guess the killer's identity.
| Directing | Charles Saunders | Director |
| Camera | Desmond Davis | Focus Puller |
| Writing | Francis Edge | Screenplay |
| Writing | John Temple-Smith | Screenplay |
| Crew | Maurice Temple-Smith | Additional Dialogue |
| Production | Robert S. Baker | Producer |
| Production | Monty Berman | Producer |
| Sound | John Lanchbery | Music |
| Crew | Eric Cross | Cinematography |
| Editing | Jack Slade | Editor |
| Art | Ray Simm | Art Direction |
| Costume & Make-Up | Jill Carpenter | Makeup Artist |
| Costume & Make-Up | Joan Carpenter | Hairstylist |
| Production | Jack Hanbury | Production Manager |
| Production | Johnny Goodman | Assistant Production Manager |
| Directing | George Fowler | Assistant Director |
| Sound | Harry Benson | Sound Recordist |
| Sound | George Burgess | Sound Supervisor |
| Camera | Freddie Cooper | Clapper Loader |
| Sound | John Lanchbery | Music Director |
| Directing | Joanna Busby | Continuity |