American GI Ernie Williams, admittedly weak-kneed, has an uncanny resemblance to British Colonel MacKenzie. Williams, also a master of imitation and disguise, is asked to impersonate the Colonel, ostensibly to allow the Colonel to make a secret trip East. What Williams is not told is that the Colonel has recently been a target of assassins. After the Colonel's plane goes down, the plan changes and Williams maintains the disguise to confuse the Nazis about D-Day.
Unfortunately the movie On the Double is not yet available on HBO Max.
| Directing | Melville Shavelson | Director |
| Writing | Melville Shavelson | Writer |
| Production | Jack Rose | Producer |
| Editing | Frank Bracht | Editor |
| Writing | Jack Rose | Writer |
| Sound | Leith Stevens | Music |
| Camera | Harry Stradling Sr. | Director of Photography |
| Sound | John Wilkinson | Sound Recordist |
| Art | Arthur Lonergan | Art Direction |
| Art | Hal Pereira | Art Direction |
| Directing | Arthur Jacobson | Assistant Director |
| Costume & Make-Up | Nellie Manley | Hair Supervisor |
| Art | Sam Comer | Set Decoration |
| Sound | Lyle Figland | Sound Recordist |
| Costume & Make-Up | Wally Westmore | Makeup Supervisor |
| Directing | Harry Caplan | Assistant Director |
| Costume & Make-Up | Edith Head | Costume Design |
| Art | Frank R. McKelvy | Set Decoration |
