What is the name of this movie??? HELP!?

WHAT IS THE NAME OF THIS MOVIE

Guy who is not rich has rich friends. I'm not sure if they're teenagers or early 20s, anyway they're hanging out and having fun. Someone then kills someone else. I think on purpose. The killer wants to kill other people. They all try to figure out who the killer is. Three guys, one girl (the girl is blonde), they are the friends. Everyone is white. So one of them is the killer, we don't know yet until the end.

So they have fun at a big house rich house, whatever, there is woods around or something. whatever. Someone knocks at the door and they all get scared (remember it's super suspenseful movie) it's one of the friends at the door. Okay so the friend that wasn't rich, his dad worked as a butler/servant at his rich friend's house!

think the butler or his son might be the killer but I'm not sure. I must also add the friend who's not rich (Who's dad is a butler) he looked like Chris Pine , but blue eyes and dark hair. very very very handsome. The movie is suspenseful and mystery and thriller. p[lease elf. the movie was made around 2010s maybe or early 2000s or 2008/9/10 i don't know help