They Met in the Dark is a 1943 British comedy thriller film directed by Karel Lamač and starring James Mason, Joyce Howard and Edward Rigby. The screenplay concerns a cashiered Royal Naval officer and a young woman who join forces to solve a murder and hunt down a German spy ring. The film features a single song sung by Phyllis Stanley, "Toddle Along" (Ben Frankel, Moira Heath). The film is very loosely based on the 1941 novel The Vanishing Corpse by Anthony Gilbert.

It was shot at Teddington Studios in London. The film's sets were designed by the art director Norman G. Arnold.