A year after her sister Melanie mysteriously disappears, Clover and her friends travel to the remote valley where she disappeared in search of answers. While exploring an abandoned visitor center, they are stalked by a masked killer and are brutally murdered one after the other… only to wake up to find themselves at the beginning of the same night. Trapped in the valley, they are forced to relive the nightmare over and over again – only each time the killer threat is different, each more terrifying than the last. As hope fades, the group quickly realizes that they have a finite number of dead, and the only way to escape is to survive until dawn.