For a movie that doesn't quite know what it's trying to say about violence, it sure knows how to say it with vigor.

A nasty little piece of B-movie trash that lacks both the verve to grab you as a guilty pleasure and the artistry to be taken seriously as a dramatic thriller.

Emile Hirsch and Zoe Kravitz, as strangers thrown together by a violent incident, enjoy an easy chemistry here, encouraging viewers to forget the menace that starts the story and, with startling violence, will end it.

Be warned. It goes all Taxi Driver at the end. Which will be jarring for some but thrillingly right for others.