Freaky Friday - Plot

Plot

A willful, disorganized teenage girl, Annabelle Andrews, awakens one Friday morning to find herself in the body of her mother, with whom she argued the previous night.

Suddenly in charge of taking care of the New York family's affairs and her younger brother Ben (whom Annabelle has not-so-affectionately nicknamed "Ape Face"), and growing increasingly worried about the disappearance of "Annabelle", who appeared to be herself in the morning but has gone missing after leaving the Andrews' home, she enlists the help of her neighbor and childhood friend, Boris, though without telling him about her identity crisis.

As the day wears on and Annabelle has a series of increasingly bizarre and frustrating misadventures, she becomes gradually more appreciative of how difficult her mother's life is, and learns, to her surprise, that Ben idolizes her, and Boris is actually named Morris, but has a problem with chronic congestion (at least around Annabelle) leading him to nasally pronounce ms and ns as bs and ds. The novel races towards its climax and Ben also disappears, apparently having gone off with a pretty girl whom Boris did not recognize, but Ben appeared to trust without hesitation.

In the climax and dénouement, Annabelle becomes overwhelmed by the difficulties of her situation, apparent disappearance of her mother, loss of the children, and the question of how her odd situation came about and when/whether it will be resolved. Finally, it is revealed that Annabelle's mother herself caused them to switch bodies through some unspecified means, and the mysterious girl who took Ben was Mrs. Andrews in Annabelle's body (to which she is restored) made much more attractive by a makeover Mrs. Andrews gave the body while using it, including the removal of Annabelle's braces, an appointment Annabelle had forgotten about (and would have missed, had she been the one in her body that day).

The book (and especially the film adaptations and its second sequel, Summer Switch) might be considered a modern retelling of Vice Versa, the 1882 novel by F. Anstey, in which the protagonists are a father and son.