Backwater (2013)

Cass and Mark are a couple on a camping trip to the distant countryside. When their seemingly secluded getaway is interrupted by an ominous scream, they start to think someone might be stalking them, and encounter two strangers who are also in the woods near them. Despite everything appearing to be harmless, they can't shake the feeling that something is wrong. The truth, however, is far more disturbing than meets the eye.