J.C. Wiatt (Diane Keaton) is a driven Manhattan career woman (nicknamed the "Tiger Lady") typical of the 1980s whose fast-paced life leaves her with no time for romance or relaxation (or as the narrator in the beginning puts it she works "5 to 9"), though she derives pleasure from her frantic schedule and demanding job. She works as a management consultant and lives with an investment banker (Harold Ramis), whose job and life are likewise hectic. Her life is thrown into turmoil when she inherits a toddler, Elizabeth (twins Kristina and Michelle Kennedy), from a deceased cousin whom she hadn't seen in over 30 years.

Caring for the child soon occupies much of her time and her career begins to suffer, culminating in the loss of her boyfriend and job. Wiatt tries to give Elizabeth up for adoption but finds that she has grown too attached to the child, forcing a reevaluation of her priorities. She moves into a house in the country in Vermont. Purchasing the home without first having seen it in person or having it inspected she finds it is riddled with problems.