A psychotic man schemes to drive his sister mad so that he can claim her inheritance, but a deadly game of cat-and-mouse begins when an imposter intervenes.
| Writing | Jimmy Sangster | Writer |
| Writing | Josephine Tey | Novel |
| Art | Don Mingaye | Art Direction |
| Art | Bernard Robinson | Production Design |
| Sound | Elisabeth Lutyens | Original Music Composer |
| Directing | Freddie Francis | Director |
| Production | Anthony Hinds | Producer |
| Camera | Arthur Grant | Director of Photography |
| Costume & Make-Up | Roy Ashton | Makeup Artist |
