A Scotland Yard detective is investigating a string of robberies and a murder, and the information he uncovers leads him to the estate of a wealthy but strange English family, who share their mansion with a group of nuns. The detective comes to suspect that neither the family nor the nuns is quite what they seem to be.
| Directing | Cyril Frankel | Director |
| Production | Horst Wendlandt | Producer |
| Writing | Derry Quinn | Screenplay |
| Writing | Stanley Munro | Screenplay |
| Writing | Edgar Wallace | Novel |
| Production | Ian Warren | Executive Producer |
| Sound | Peter Thomas | Music |
| Camera | Harry Waxman | Director of Photography |
| Editing | Oswald Hafenrichter | Editor |
