While on holiday in Istanbul, tragedy strikes, and suddenly the comfortably middle-aged, middle-class Amy is left stranded and a widow. Martha, a young American novelist, kindly helps her, but upon their return to England, Amy is ungratefully reluctant to maintain their friendship—on home soil she realizes that in normal circumstances, Martha isn't the sort of person she would be friends with. But guilt is a hard taskmaster, and Martha has a way of getting under one's skin.