I’m going to cover both the original book Coraline by Neil Gaiman, and the movie adaptation Coraline directed by Henry Selick. The movie is fairly faithful to the spirit of the book, minus the (in my opinion) unnecessary addition of Wybie (who is too instrumental in rescuing Coraline at the very end, when she is capable of rescuing herself).
Coraline, a young girl, moves into an old house with her parents, which is shared with a number of strange characters. One day she finds that a door in the living room which had previously opened to a bricked-up wall now gives her entrance to a duplicate of her own house, complete with her Other Mother and Other Father. At first she likes the new place, which is more interesting than her normal life (her intense boredom and dissatisfaction with her distracted parents and humdrum life is what makes her a prime candidate for being enticed to go somewhere new, like many Girls Underground). But she soon realizes that her Other Mother has less-than-maternal intentions towards her (including the now-infamous desire to sew buttons into her eyes).
Coraline is accompanied at times by a cat that can move between the worlds, but can only talk in the Otherworld. She returns several times to her home, between visits to the Otherworld. She encounters many strange and dangerous things along the way, and takes on an additional task of helping the spirits of other children the Other Mother has captured. Eventually, she has to beat the Other Mother at her own game (literally) to win back her stolen parents and return to the world she came from. (And even after that, must defeat her one last time when she is followed back to the ‘real world’.)
The book is a particularly creepy version of the archetype, and the movie only somewhat less so.