London in the year 1946: Maurice Bendrix, a novelist, meets his best friend Henry Miles. During World War II, Maurice had an affair with Sarah Miles, the wife of Henry, who abruptly broke off the romance in 1944. But now, Bendrix's obsession with Sarah is rekindled and he hires a man to investigate Sarah. That way Maurice gets her diary, what gives information about the reason for their separation: During a bombing raid, Sarah struck a bargain with God that she would end the affair if Maurice's life were spared. When Maurice now reappears in her life, she fears that being near him would be too great a temptation and realizes that her promise to God has become impossible for her to keep.