A married newspaper editor, Paul Pearson (Patrick Holt), is having an affair with Diana, a female reporter. Pearson has been using an old army friend, Bill Forrest, as an alibi, telling his wife (Honor Blackman) that he is with Forrest while he really visits Diana.

When Pearson decides to end the affair he asks Forrest to cover for him one more time but when on the same night Forrest is murdered suspicion naturally falls on Pearson, and his web of deceit begins to unravel.