A girl lives in a house with her parents. There is a cellar door in the house, and her parents warn her to never, ever, open it because she's not ready to see what's behind it.
What is on the other side of the door that her parents don't want her to see?
The girl is locked in the cellar. Her parents are both crazed people who thought the best way to protect their daughter would be by locking her in the cellar since she was born. On the other side of the door is the rest of the house, and the outside world.
A young woman is attending her mother's funeral. While there, she meets a man she has never seen before and falls in love immediately. After the funeral she tries to find him but cannot. Several days later she kills her sister. Why does she kill her sister?
She killed her sister hoping to see this man at her sisters funeral.
Note: If you thought of this answer easily you may be a psychopath