Scotland Yard detectives attempt to solve a spate of safe robberies across England beginning with clues found at the latest burglary in London. The film is notable for using a police procedural style made popular by Ealing in their 1950 film The Blue Lamp. It is known in the US as The Third Key.
| Directing | Charles Frend | Director |
| Camera | Roy Gough | Still Photographer |
| Editing | Gordon Stone | Editor |
| Writing | Robert Barr | Screenplay |
| Production | Michael Balcon | Producer |
| Writing | Janet Green | Screenplay |
| Production | Thomas N. Morahan | Associate Producer |
| Art | Edward Carrick | Art Direction |
| Costume & Make-Up | Anthony Mendleson | Costume Design |
| Sound | Gerard Schurmann | Original Music Composer |
| Camera | Gordon Dines | Director of Photography |
| Costume & Make-Up | Harry Frampton | Makeup Artist |
| Costume & Make-Up | Daphne Martin | Hairstylist |
