Five college students - Ash Williams, his girlfriend Linda, his sister Cheryl, their friend Scotty, and Scotty's girlfriend Shelly - drive out to a remote, rundown cabin in the Tennessee mountains. As night falls, the cellar trapdoor suddenly flies open. Scotty and Ash investigate the basement and discover an ancient book bound in human skin, known as the Naturan Demanto (later recognized as the Necronomicon), along with a tape recorder left behind by an archaeologist.

Playing the tape releases the recorded voice of the researcher translating ancient Sumerian resurrection incantations. The spoken words awaken a malevolent demonic force inhabiting the surrounding forest. Cheryl is the first victim; she flees into the woods after hearing strange voices, where the possessed trees attack her. She escapes back to the cabin, but the only bridge connecting them to safety has collapsed.

Cheryl rapidly transforms into a Deadite, stabbing Linda in the ankle with a pencil before Ash and Scotty trap her in the fruit cellar. Shelly is attacked next, turning into a rabid ghoul that Scotty is forced to dismember with an axe. Scotty leaves to find another path through the forest but returns fatally wounded by the trees. Linda succumbs to infection, leaving Ash alone against his possessed friends. After decapitating Linda, Ash faces down Cheryl and a resurrected Scotty in the living room. In a desperate move, Ash grabs the book and tosses it into the fireplace. The burning tome causes the demons to rot, melt, and burst into gory heaps of flesh.

With dawn breaking, Ash stumbles out of the decimated cabin into the morning light, believing his nightmare is finally over. As he breathes a sigh of relief, the camera takes the first-person perspective of the unseen demon, roaring through the woods and slamming directly into Ash as he screams. The abrupt cut to black confirms that burning the book only destroyed the physical possessed bodies, not the ancient evil itself. Ash did not truly win; the forest remains cursed.