21 Days (also known as 21 Days Together, The First and the Last and Three Weeks Together) is a 1940 British drama film based on the short 1919 play The First and the Last by John Galsworthy. It was directed by Basil Dean and stars Vivien Leigh, Laurence Olivier and Leslie Banks. The film was renamed 21 Days Together for the American market.

Plot

Larry Darrant, the black sheep of his family, returns home to London from an unsuccessful business venture in Kenya and embarks on an affair with a married woman, Wanda. When Wanda's long-absent husband, Henry, who is Russian, shows up, he tries to extort money from the lovers, and pulls a knife on Larry when he refuses to pay. In the ensuing fight Henry is accidentally killed when he strikes his head on the fire fender.