what is this movie called it was on in december i think in the UK?
its an american murder mystery movie about a girl called sally who stays with her friend 4 a sleepover in the tent and they play strip poker with her friend's brother and his friend.
her friend decides 2 sleep in the house but sally wants 2 sleep in the tent on her own so she does and gets murdered and the brother gets hypnotized by a psychologist who makes him believe that he murdered sally.

sounds really creepy i know but i wanna know the name of it i think it was based on a true story? thanks