Flatland.

Wiki:

Flatland: A Romance of Many Dimensions is an 1884 satirical novella by the English schoolmaster Edwin Abbott Abbott. Writing pseudonymously as "a square", Abbott used the fictional two-dimensional world of Flatland to offer pointed observations on the social hierarchy of Victorian culture. However, the novella's more enduring contribution is its examination of dimensions; in a foreword to one of the many publications of the novella, noted science writer Isaac Asimov described Flatland as "The best introduction one can find into the manner of perceiving dimensions." As such, the novella is still popular amongst mathematics, physics, and computer science students.

Several films have been made from the story, including a feature film in 2007 called Flatland. Other efforts have been short or experimental films, including one narrated by Dudley Moore and a short film with Martin Sheen titled Flatland: The Movie.