Five Michigan State University students—Ash Williams, his girlfriend, Linda; his sister, Cheryl; their friend Scott; and Scott’s girlfriend Shelly—vacation at an isolated cabin in rural Tennessee. Approaching the cabin, the group notices the porch swing move on its own but suddenly stop as Scott grabs the doorknob. While Cheryl draws a picture of a clock, the clock stops, and she hears a faint, demonic voice tell her to “Join us”. Her hand becomes possessed, turns pale and draws a picture of a book with a demonic face on its cover. Although shaken, she does not mention the incident.
When the cellar trapdoor flies open during dinner, Shelly, Linda, and Cheryl remain upstairs as Ash and Scott investigate. They find the Naturan Demanto, a Sumerian version of the Egyptian Book of the Dead, along with an archaeologist’s tape recorder. Scott and Ash joke around with the items and take them upstairs. Scott plays a tape of incantations that resurrect a demonic entity. Cheryl yells for Scott to turn off the tape recorder, and a tree branch breaks one of the cabin’s windows. Later that evening, an agitated Cheryl goes into the woods to investigate strange noises. She gets attacked, stripped, pinned to the ground, and raped by demonically possessed trees. When she manages to escape and returns to the cabin bruised and anguished, Ash agrees to take her back into town, only to discover that the bridge to the cabin has been destroyed. Cheryl panics as she realizes that they are now trapped and the demonic entity will not let them leave. Back at the cabin, Ash listens to more of the tape, learning that the only way to kill the entity is to dismember a possessed host. As Linda and Shelly play Spades, Cheryl correctly calls out the cards, succumbs to the entity, and levitates. In a raspy, demonic voice, she demands to know why they disturbed her sleep and threatens to kill everyone. After she falls to the floor, the group checks on her; Cheryl stabs Linda in the ankle and throws Ash into a shelf. Scott knocks Cheryl into the cellar and locks her inside.
Everyone fights about what to do. Shelly becomes paranoid upon seeing Cheryl’s demonic transformation. She lies down in her room but is drawn to look out of her window, where a demon crashes through and attacks her. Shelly becomes a Deadite and scratches Scott’s face. Scott throws her into the fireplace, briefly burning Shelly’s face. As she attacks him again, Scott bisects part of her wrist with a knife and then she bites off her own mangled hand. Scott stabs her in the back with a Sumerian dagger, apparently killing her. When she reanimates, Scott dismembers her with an axe and buries the remains. Shaken by the experience, he leaves to find a way back to town. He shortly returns mortally wounded; he dies while warning Ash that the trees will not let them escape alive. When Ash checks on Linda, he is horrified to find that she has become possessed. She attacks him, but he stabs her with a Sumerian dagger. Unwilling to dismember her, he buries her instead. She revives and attacks him, forcing him to decapitate her with a shovel. Her headless body bleeds on his face as it tries to rape him, but he pushes it off and retreats to the cabin.
Back inside, Ash is attacked by Cheryl, who has escaped the cellar, and the reanimated Scott. He shoots Cheryl several times, gouges Scott’s eyes out, and pulls out a branch lodged in Scott’s stomach, causing him to bleed out. The Deadites attack, bite, and beat Ash with a fire iron. Ash throws the Naturan Demanto into the fireplace, and the Deadites stop their attack. As the book burns, Scott, Cheryl, and the book gruesomely decompose. Demonic hands protrude from both corpses, and Cheryl’s decomposed body falls and splatters in front of Ash, leaving him covered in her and Scott’s entrails. He hears a voice say “Join Us” but relaxes when it dies away. As day breaks, Ash stumbles outside. Before he can leave, an unseen surviving entity rapidly trails the forest and runs through the cabin, breaking the cabin doors and attacks him from behind, apparently killing him.