Can you help me find this film?

We watched back in high school, in English. All I can remember is that there's a young man who has an abusive step dad or something like that, he moves out, and I think he goes to live with his sister. Her partner doesn't seem to like him being there and he moves out and ends up homeless.. I remember at the end, I'm pretty sure there's a murderer who's been killing homeless people and bodies are found under his floorboard? Vague details, I know but if anyone knows what film this is I'd be grateful. Must be based off a book as we watched it in English but I can't remember much about it