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

She grows increasingly worried about the disappearance of "Annabel," who appeared to be herself in the morning but has gone missing after leaving the Andrews' home, and 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 Annabel has a series of increasingly bizarre and frustrating adventures, she becomes gradually more appreciative of how difficult her mother's life is.

She learns, to her surprise, that Ben idolizes her, and Boris is actually named Morris, but has a problem with chronic congestion (at least around Annabel) leading him to nasally pronounce ms and ns as bs and ds.

It themes include empathy and understanding, generational conflict, self-discovery, love and family bonds, and coming of age.

In A Billion for Boris (October 1974), Annabel and her friend Morris/Boris discover a TV set that tunes into future broadcasts and begin betting on horse races.

In the story an orderly schedule oriented 13-year-old schoolgirl Hadley, and a spontaneous easy-going teacher named Ms. Pitt inexplicably swap bodies.

In the first film, the screenwriter and original book author Mary Rodgers added a hobby for Annabel which includes an important competition, for which her mother has lack of experience and skill, serving as the climax of the movie.

Additionally, a simultaneous important event for the mother character was added to the 2003 film, to include her wedding rehearsal dinner.

In the first movie, Morris is changed to a character named Boris and is adjusted to be Annabel's love interest, rather than beginning the story as a rival of hers.

The movie stars Vince Vaughn and Kathryn Newton as an infamous serial killer and a tormented high school student, respectively; who switch bodies after the former stabs her with an ancient dagger.

Directed by Christopher Ashley, with choreography by Sergio Trujillo, the cast features Emma Hunton (as the daughter Ellie), Jason Gotay and Heidi Blickenstaff (as the mother Katherine).