For a truly terrifying Halloween horror flick, British thriller Eden Lake should fit the bill. It's about a couple who goes away for the weekend on a nice, romantic, idyllic getaway that ends up shattered by... oh, you know, the teenagers who turn out to be torturous murderers. Our protagonists, a (formerly) happy couple, have to literally fight for their lives against a band of heathens, who at first seem like nothing more than bratty, entitled youths; then they seem like trouble-making pranksters. But when it turns bloody and brutal, you realize even seemingly harmless teens can be evil. Kids today... they're always trying to torture and murder innocent people for no reason at all. I remember when I was young, we would only do that if someone deserved it. You know, like Dexter. Seriously, though, remember Lord of the Flies and Pet Semetary? Anytime you have young people as the villains in a movie, it's freaking disturbing in the most unsettling way.

Reviews by People Who've Actually Seen It:
Rotten Tomatoes