If a Tree Falls (2010)

Siblings, Brad and Lisa Carpenter, along with two lifelong family friends, Will and Vanessa, set out road-tripping to an annual family reunion. They make the decision to find a place to stop and camp for the night. What ensues is a violent disturbance by six masked assailants, without motive or reason. The group find themselves living a night of psychological games and physical terror, and as morning dawns; the reality of what will come is more terrifying than anything the group could have ever imagined.