Fifi Brown is headstrong. Her mother is appalled when she secretly marries Dan Reynolds, a handsome but itinerant bricklayer. But Dan and Fifi move to a seedy South London flat determined to be happy. Despite initial feelings of horror at her new surroundings, Fifi finds London and the freedom from her middle-class family background exhilerating. Insatiably inquisitive, Fifi is fascinated by her new neighbors and wants to know what goes on behind all those shabby front doors. But when she tries to help a young girl who has been abused by her father, Fifi unwittingly unleashes a chain of events which will not only bring heartache to her and Dan, but terrible danger to the whole neighborhood.