One year after her brother mysteriously vanished during a hiking trip, Justin Harper returns to the remote mountain valley where he disappeared. Determined to uncover what really happened, she brings three friends with her to investigate the abandoned visitor center where his backpack was found.

But the valley holds more than secrets.

Inside the crumbling building, the group is hunted by a masked killer who brutally murders them one by one... only for Justin to suddenly wake up at the beginning of the same evening.

The night has reset.

Trapped in the valley, Justin and her friends are forced to relive the nightmare again and again. Each time they die, the night restarts-but the rules change. The killer evolves, learning from every mistake they make. New traps appear. New horrors wait in the dark. And with each reset, the valley becomes more dangerous.

As hope fades, the group discovers the terrifying truth: they only have five deaths before the loop ends forever.

To escape, they must survive until dawn.

But the valley isn't just hunting them.

It's studying them.

And someone-or something-has been learning how to kill.