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 realises 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...