In 1942, a cargo ship jammed with British evacuees from Singapore is sunk by a Japanese sub. A small lifeboat carries a beautiful woman, an army officer, a bigoted administrator and a black seaman. Only the seaman knows the woman is a nun. The men reveal their true selves under the hardships of survival. Told in flashback while, in the present, the officer (Biscuit) searches for the nun (Sea Wife).