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 find themselves being stalked by a masked killer and brutally murdered one by one… only to wake up earlier that same night. Trapped in the valley, they are forced to relive the nightmare over and over again, each time with a different killer threat, each more terrifying than the last. As hope fades, the group quickly realizes that they have a finite number of dead left and the only way to escape is to survive until dawn.