One of those children is actually Wybie's grandma's lost twin.
She obviously refuses, but the Other Mother doesn't like that decision and traps her in a small room behind a mirror, where she meets the ghosts of 3 children, who got fooled by the Other Mother and lost their eyes and souls.
Meanwhile her real parents got kidnapped by the Other Mother.
With the cat and Other Wybie's help and advices she finally manages to beat the Other Mother. When she goes back in the real world her parents are safe but don't remember anything.
She now has to get rid of the key that opens the small door. She tries to throw it in a very deep well, but somehow the Other Mother's hand got through the door and tries to pull Coraline into the well, but Wybie arrives and saves her throwing the skeletal hand and the key, down the well.
Coraline came out in 2009, is directed by Henry Selick and sponsored by Laika. It's inspired by 2002 Neil Gaiman's book Coraline, both of them are dark-fantasies. This movie has a dark hidden side, because it looks like a movie for kids, but it has some characters with twisted minds, and a psychological depth that leads to a light anguish.