A college student named Scotty drives his friends Ash, Cheryl, Shelly, and Linda to a rented cabin in the Tennessee mountains. On their way, Scotty nearly collides with an oncoming truck. Later, the group crosses a dilapidated bridge, marked “dangerous.” At the ramshackle cabin, Cheryl sketches a drawing of the living room clock, but it suddenly stops, and she is possessed to draw a strange figure. At dinner, the friends are startled when a trap door to the cellar opens on its own. Scotty volunteers to investigate and frightens his friends by not responding to their call. When Ash creeps downstairs and reunites with Scotty, the boys discover a shotgun, ammunition, a reel-to-reel tape recorder, an ancient book, and a dagger with a skull-encrusted handle. Back upstairs, the friends play the recording and hear the dictation of an archeologist; the man excavated ruins in Kandar before moving with his wife to the Tennessee woods for seclusion. At the cabin, the archeologist studied one of his Kandar discoveries, the Book of the Dead, which is made of human flesh and written in human blood. The book details the burial practices of ancient Sumerians and lists funeral incantations, which give demons permission to possess the living. Although Cheryl turns off the recording, Scotty insists on resuming the tape, which transmits deadly verses as steam rises from the ground outside. Cheryl screams, again shuts off the tape, and a tree branch smashes through the window. Ash scolds Scotty for causing trouble. Later that evening, Ash presents his girl friend, Linda, with an antique necklace adorned with a small magnifying glass. Meanwhile, Cheryl hears a strange sound beckoning her outside and leaves the cabin to search for its origin. Trees spontaneously fall as vine-like branches wrap themselves around the girl, pinning her to the ground and raping her. She breaks free and runs through the woods, chased by an invisible demon. Escaping into the cabin, Cheryl tells her disbelieving friends that the trees are possessed and demands that her brother, Ash, drive her back to town. On the way, Ash and Cheryl discover the “dangerous” bridge has been destroyed, and they return to the cabin. There, Ash listens to the archeologist’s recording on his own, through an earpiece. The man’s voice reports that his wife has become a “host” to a Kandar demon, but the only way to destroy the possessed is to dismember their bodies. As Shelly and Linda play a card guessing game, Cheryl astonishes them by naming each card correctly, then turns toward her friends to reveal her demonic face. Suspended in mid-air, Cheryl speaks with an angry male voice, demanding to know why the youths have awakened the undead. The demon vows to possess the new inhabitants as Cheryl falls to the ground, lifeless. However, she suddenly comes to and stabs Linda’s ankle with a pencil. Cheryl then goes after her brother, Ash, but Scotty uses an ax to force her into the cellar and locks the trap door with a chain. There, Cheryl growls and Scotty promises his friends they can leave in the morning. When Shelly reluctantly goes to her bedroom, a force from outside breaks the window and she disappears. Scotty searches for her, only to discover she has also been possessed. Shelly cuts through his face with her long fingernails and falls into the fireplace, but Scotty drags her to safety. In turn, Shelly strangles Scotty, wielding the skull dagger in her other hand, but Scotty pulls a knife and cuts through her wrist. She eats her own flesh to sever the hand from her arm. Scotty stabs her in the back and she collapses, spitting white fluid. When the demon revives, Scotty hacks her to pieces with his ax, and her body parts wriggle on the ground. Scotty insists on burying Shelly, so he and Ash drag her remains into the woods. Although Scotty wants to leave the cabin immediately, Ash declares they must wait because his girl friend, Linda, is unable to walk with her ankle wound. When Ash goes to Linda’s bedside, the lesion suddenly increases in size, and she sits upright, possessed. Ash escapes her room to discover Scotty wounded and muttering a warning that they are all going to die. Ash demands to know an alternative route to town, bypassing the bridge, but Scotty says the trail is the only other way, and it is thick with possessed trees. As Linda cackles, Ash smacks her; however, when he holds the shotgun to her head, he is unable to pull the trigger. Linda’s face transforms back to normal and she begs for help. The couple then hears Cheryl’s regular voice, asking to be let out of the cellar. As Ash peers under the trap door to check on his sister, the demon grabs his neck, but he breaks free. Just then, Linda becomes repossessed and Ash drags her into the woods. He returns to the cabin for Scotty, vowing they will return to civilization when the sun rises. However, Linda slices through Ash’s arm with the demon dagger, and licks his blood from the blade. The couple fights for the weapon and Ash throws his girl friend to the ground, impaling her on the knife. To ensure that Linda is truly dead, Ash drags her to a shed and attempts to dismember her with a chainsaw, but he sees the looking glass necklace he gave her and stops. He buries her, but she exhumes herself, using her fingernails to slice through his ankles. Ash defends himself with a wood beam and decapitates her. Back in the cabin, Cheryl breaks out of the cellar. Ash returns and searches the house with a shotgun, then fires at his sister’s possessed body. In need of more ammunition, he creeps into the cellar, now flooding with blood. A gramophone and film projector spontaneously start operating then explode as Ash remembers the archeologist’s finding: the possessed can only be killed through dismemberment. Upstairs, he moves his hand toward his reflection in a mirror, only to discover a liquid surface. Screaming and terrified, he fires the shotgun through a window and retrieves Linda’s looking glass necklace from his pocket. Just then, Cheryl’s hands break through the door, and Scotty awakens, possessed. As he raises Ash into the air by his throat, Ash pokes Scotty’s eyes out. With Cheryl beating him on the back with a fire poker and Scotty eating his flesh, Ash uses Linda’s necklace to drag the Book of the Dead toward him, then throws it into the fire. The book transforms into a ghoulish face as the flesh of Cheryl and Scotty melts away. Demon hands thrust out of their stomachs, covered in blood and bile. As the sun rises, the living room clock resumes ticking. Ash leaves the cabin, clutching Linda’s necklace, but an invisible, evil force rushes through the woods and overpowers him.