A charming British anthropology Professor Bruce Patterson (Terry-Thomas) has to live with Helen Bushmill (Celeste Holm), his fiancée. Helen is away traveling, and has failed to tell him that she has a seventeen-year-old daughter Libby (Tuesday Weld), who shows up at her mother's home unaware that Helen is engaged. Meanwhile he has to resist the advances of the neighborhood ladies who barge in unexpectedly. At the same time, Patterson must deal with the continual invasions of Mike (Richard Beymer), his cynical neighbor and law student, who soon develops a crush on Libby. Intertwined in the story is Mike's persistent dachshund, determined to bury the professor's prize possession of a rare dinosaur bone.