Name of the movie?

I can't remember the whole plot of the movie, since I watched it a long time ago but here are some scenes that I do remember:

A girl and her younger brother are staying at their uncle and aunt's home (after they lost their parents I think), but the uncle begins to give drugs to sister and brother. He drugged her at the parking garage I think and then locked her in the basement. She escapes with her brother and in the end, she ends up killing her uncle.

Does anyone know the title of this movie?