In wartime England, circa 1941, poorly-armed tugs are sent into "U-Boat Alley" to rescue damaged Allied ships. An American named David Ross arrives to captain one of these tugs. He's given a key by a fellow tugboat-man -- a key to an apartment and its pretty female resident. Should something happen to the friend, Ross can use the key.
| Writing | Jan de Hartog | Novel |
| Directing | Carol Reed | Director |
| Writing | Carl Foreman | Writer |
| Costume & Make-Up | Beatrice Dawson | Costume Design |
| Art | Geoffrey Drake | Art Direction |
| Production | Aubrey Baring | Associate Producer |
| Production | Carl Foreman | Producer |
| Sound | Malcolm Arnold | Original Music Composer |
| Art | Wilfred Shingleton | Production Design |
| Editing | Bert Bates | Editor |
| Camera | Oswald Morris | Director of Photography |
| Crew | Peter Peake | Technical Advisor |
