Mumfords are a middle-class couple, living in suburban Sutton on the outskirts of London with their young son. Reading the newspaper, they become aware of a young woman seeking a place as a "paying guest", or lodger. To supplement their income they decide to take a tenant, named Louise Derrick, who is in need of a place to live due to disagreements with her immediate family. Louise, who is poorly educated and bad-tempered, is being romantically pursued by two men: Mr Bowling, who is courting Louise's stepsister Cecily, and Tom Cobb.