One day Isabel finds a box in her mother's closet and, inside, a photograph of a girl dressed in old-fashioned clothes. Ten-year-old Bel is enchanted to discover that the girl is her great-grandmother Beatrice, her Bisa Bea, and that she and her great-grandmother look very much alike.

Bel convinces her mother to let her borrow the treasured photo promising to look after it carefully. To her dismay, by the time she returns home from school, the picture is missing. But something unusual has happened. Suddenly it is as if Bisa Bea is alive inside her, telling Bel what life was like when she was a girl. Bel loves hearing the stories about the old days -- until Bisa Bea starts to tell her how to behave. Bel learns that her great-grandmother lived in a very different time, when girls were expected to be proper young ladies.