A sister and her disturbed twin are implicated in a murder and a police detective must figure out which one's the killer.
| Directing | Robert Siodmak | Director |
| Production | Nunnally Johnson | Producer |
| Sound | Dimitri Tiomkin | Original Music Composer |
| Writing | Nunnally Johnson | Writer |
| Camera | Milton Krasner | Director of Photography |
| Editing | Ernest J. Nims | Editor |
| Costume & Make-Up | Mary Freeman | Hairstylist |
| Art | Hugh Hunt | Set Decoration |
| Visual Effects | Eugen Schüfftan | Visual Effects |
| Sound | Frank Skinner | Music |
| Costume & Make-Up | Norbert A. Myles | Makeup Artist |
| Art | Duncan Cramer | Production Design |
| Costume & Make-Up | Irene Sharaff | Costume Design |
| Sound | Fred Lau | Sound |
| Sound | Arthur Johns | Sound |
| Crew | Paul K. Lerpae | Special Effects |
| Crew | Phyllis Loughton | Dialogue Coach |
| Writing | Vladimir Pozner | Original Story |
| Crew | Devereaux Jennings | Special Effects |
