The movie was great it was scary to watch alone though, Rebecca who is the older sister who leave home at age of 10 after her father left but actually killed by Diana (the ghost). She has a younger brother named martin and living with their mom. Their mom was depressed and was sent to mental Constitution when she's young, she met Diana there and became friends with her.
But eventually Diana died and use their mom to live in the dark. Their mom was not in the state of mind and that's how Diana use her, she can only move in the dark and never in the light.