During a celebration party at her family's lodge on Blackwood Mountain, a cruel prank causes Hannah Washington to flee into the woods. Hannah's twin sister Beth finds her, but the two are pursued by a flamethrower-wielding stranger, resulting in them falling off a cliff. Despite a search, their bodies are never found and they are declared missing.

A year later, Hannah and Beth's brother Josh invites the group from the previous party—Hannah's friend Sam Giddings, Josh's friend Chris Hartley, Chris' crush Ashley Brown, couple Emily Davis and Matt Taylor, Emily's ex-boyfriend Mike Munroe, and Mike's new girlfriend Jessica Riley —back to the lodge. Despite tensions between members of the group and reservations about returning after the previous year's events, all seven accept Josh's invitation. Each member of the group arrives at the lodge via cable car before engaging in separate activities on the mountain.

As the night progresses, Mike and Jessica tryst at a guest cabin, where Jessica is abducted by an unseen figure. Mike pursues her captor to an abandoned sanatorium, where he uncovers documents detailing a 1952 cave-in that trapped a group of miners. Mike finds Jessica either dead or alive, but the elevator she is in plummets, leading him to believe she has died. Meanwhile, Josh, Ashley, Chris, and Sam find themselves terrorized by a masked man in the lodge. Josh is seemingly killed after being bisected in a torture device set up by the masked man, who then pursues Sam through the lodge's lower levels. The man later orders Chris to shoot Ashley or himself under the threat of both of them being killed by large saw blades. Matt and Emily, having been alerted to the masked man's attack, discover that the cable car has been locked; instead, the two head to a radio tower to request help. Although their signal is received, they are informed that no rescue can occur until dawn due to a storm. An unknown creature causes the radio tower to collapse into the mines, separating Matt and Emily. Emily stumbles across the site where Hannah and Beth fell the previous year, and, to her horror, finds Beth's severed head nearby. She is later chased by the creature out of the mines.

Mike reunites with Sam just as the masked man reappears and reveals himself to be Josh, who orchestrated the events at the lodge as a revenge prank for his sisters' presumed deaths. Josh denies any involvement in Jessica's death, but Mike restrains him in a shed to await the police. Later, Sam, Mike, Chris, Ashley, and—if she survived her escape from the mines—Emily are confronted at the lodge by the Stranger. The Stranger reveals the creatures that abducted Jessica and attacked Matt and Emily are wendigos, former humans who became feral after resorting to during the 1952 cave-in. Chris and the Stranger head to the shed to retrieve Josh but find him missing. On the way back, the Stranger, and potentially Chris, are killed by a wendigo. While perusing the Stranger's research, Emily—if she was bitten during her escape—reveals the injury; Mike may shoot her out of fear of infection. Believing Josh holds the key to the cable car, Mike heads to the sanatorium to retrieve it. The others follow, though Ashley and Chris may fall victim to a wendigo attack along the way.

Sam and Mike find Josh in the mines, whose deteriorating mental state causes him to hallucinate his sisters and his psychiatrist, Dr. Alan Hill (Peter Stormare). Mike attempts to guide him to safety, but they are separated when a wendigo attacks Josh. He is killed unless Sam has uncovered enough clues to reveal the truth: the lead wendigo is Hannah, who survived her fall but transformed after consuming Beth's remains. If Jessica and/or Matt have survived, they regroup and attempt to escape the mines while evading Hannah. Mike and Sam return to the lodge and join the remaining survivors in the basement, but find it overrun by wendigos, including Hannah. When a fight between the wendigos causes a gas leak, Mike and Sam work together to ignite an explosion that destroys the lodge, killing Hannah, the other wendigos, and possibly some of the group. Following the explosion, rescue helicopters arrive to retrieve whoever has survived until dawn.

Main characters

Ashley Character

Ashley Brown

A curious academic with a big imagination who loves books and gets scared easily.

Chris Character

Christopher Hartley

A methodical and loyal nerd with a tendency to clown around and pull pranks.

EmilyCharacter

Emily Davis

A brash and adamant fashion lover who uses her smarts to get her way.

Jessica Character

Jessica Riley

A flirty, airheaded party girl with a larger-than-life personality.

Josh Character

Joshua Washington

‎A mysterious, complex film enthusiast who has been struggling to cope with the disappearance of his sisters.

Matt Character.

Matthew Taylor

A motivated, gentle - yet protective - young athlete.

Mike Character

Michael Munroe

A popular, driven young man who is a fan of women, attention, and taking matters into his own hands.

Sam Character

Samantha Giddings

A nature-loving pacifist who cares for her friends, often acting as the group's mediator.