Two young campers wander through the woods, noting there are no animals or birds around, until they stumble upon a pile of mutilated deer carcasses left on the trail and are chased by a mutilated deer that collapses at their feet just as a large swarm of birds sounds in the distance.
In southern New Jersey, Richard Vineyard, [Stephen Moyer], his wife Cynthia Vineyard, [Mia Kirshner], their daughter Sadie Vineyard, [Allie MacDonald], and their young son Danny Vineyard, [Peter DaCunha], leave their suburban home for a family camping trip in the sprawling Pine Barrens. On the drive, they glimpse a mutilated deer crossing the road and soon check into a crowded commercial campsite where plenty of louder, pushy campers share the space. While Richard wrestles with a flashback from his own past in this very place, the family tries to settle in for a quiet night. A fellow camper’s story about the Jersey Devil stirs unease, and some campers play a cruel prank that lands with embarrassment on Richard, who overreacts, heightening tension within the family.
That night, Richard dreams he is chased across an open field, only to be awakened by Cynthia in the middle of the forest—she had wandered from the tent while asleep. He accuses her of infidelity, a charge she struggles to understand as he later apologizes. As Cynthia returns, Richard heads out again and witnesses a deer carcass fall from a tree. It’s revealed in time that Cynthia is his second wife, the prior loss of Sadie’s mother already shaping their bond, and Richard is already taking pain medication for a wound he sustained before the trip. The sense of unease deepens as a missing camper from the prank is discovered to be part of the night’s fallout.
The group encounters a missing camper, and Richard, looking increasingly frail, leads the family away from the trails into more remote territory in search of a safer setup. Danny finds the body of the missing camper, a decomposed dog carcass, and a ruined campsite, but says nothing. Richard becomes more erratic and irritable, while Cynthia remains focused on getting through the night. They realize someone has been following them; Ryan, [Erik Knudsen], has been secretly communicating with Sadie by cell phone, a fact Richard tries to uncover and confiscate when he can. The family decides to press on, with Cynthia announcing they plan to go home the next day, but Richard’s deteriorating condition—both physically and mentally—casts a heavier shadow over the trip.
Richard’s condition worsens as he sleeps and wakes in a haze, his wound connected to the dog that attacked the family back home. He sleepwalks again, and this time the fog seems to part into a pale mist where the Jersey Devil appears and closes in on the family. Cynthia urges everyone to leave the area, and they push ahead, but Danny and Richard disappear from view. Cynthia calls the police, and Sadie and Cynthia discover Ryan’s disemboweled corpse with Richard’s knife nearby. Danny’s body is later found face down in the river, and the family fights to revive him.
Richard returns, violent and ravenous, attacking Cynthia and breaking her leg. Sadie manages to knock him unconscious and ties him up, while Danny and Sadie set out to find help. Cynthia, exhausted and in pain, slips into unconsciousness as Richard again sees the Jersey Devil and breaks free of his bindings. A desperate moment follows when Cynthia knocks him out with a rock, only to discover he has vanished when she checks on him minutes later, and she is knocked down by something unseen.
Sadie and Danny are eventually rescued by a hunter who guides them back to their parents. The police recover the bodies of the missing campers. Richard tears into the hunter and grabs the rifle, aiming it toward his family as he spots the Jersey Devil looming behind them—an image now visible to all. The sheriff, [David Keeley], believes Richard is aiming at Sadie and fires, killing him instead, while the Jersey Devil attacks and kills the sheriff. A forest ranger witnesses the creature’s assault and flees the scene, the danger still very real.
Sometime later, Sadie is interviewed by authorities, and her account of the terrifying events is treated as psychological trauma. Undeterred, she joins the ranger and a band of hunters with the intent to track and hunt the Jersey Devil, determined to face what she witnessed rather than let it fade into rumor. The film closes on a note that mixes lingering fear with a resolve to confront the unknown, leaving the family’s future marked by the memory of that night in the Pine Barrens and the possibility that the Jersey Devil still stalks the woods.
