Lots of slogans such as "Be like Dad, Keep Mum" and "Keep it under your Hat" are visible on the walls in various scenes to reinforce the plot of this British wartime movie illustrating how gossipy talk can result in unknowingly giving valuable information to Nazi spies.

When his wife stops writing to him and his letters are returned unanswered, Dan becomes extremely concerned about her welfare. He returns home but is only able to meet with her briefly before she is found murdered. Dan is the obvious suspect but has only 36 hours to find out who murdered her. In so doing he uncovers a shocking catalogue of his wife's past affairs and an identity that he knew nothing about.

Losing out to Dr. Bingham (Michael Medwin) in a competition for house surgeon when he offends a member of the board, young Dr. Simon Sparrow (Dirk Bogarde) finds himself going from post to post, filling in for other physicians. At one distant country post, he is taken aback when he works with a patient whose husband died after Simon treated the man years before. In another hospital, Simon examines a surprisingly mature teen and also tries courting devoted nurse Nan McPherson (Shirley Eaton).

An innocent man is released from prison after 12 years and tracks down the witnesses who lied about him in court.