Barbra and Johnny, siblings, drive to a cemetery in rural Pennsylvania to visit their father’s grave, but the quiet trip turns horrific when a pale man in a tattered suit kills Johnny and attacks Barbra. Barbra barely escapes to a nearby farmhouse, only to discover the resident’s corpse lying half‑eaten on the stairs. A growing horde of ghouls closes in around the house, and a stranger named Ben arrives, initially mistaking Barbra for the homeowner. He fights off several ghouls, boards up the windows and doors, and, while searching the home for supplies, finds a lever‑action rifle.
A nearly catatonic Barbra learns that people have already sought shelter in the cellar: Harry, his wife Helen, and their young daughter Karen, who was bitten and is gravely ill after a ghoul attack on their car; a couple, Tom and Judy, who fled after hearing an emergency broadcast about brutal killings. The refugees listen to radio and television reports of an army of cannibalistic corpses sweeping the East Coast and of armed men patrolling the countryside to exterminate the living dead. Reports confirm that ghouls can die again from heavy blows to the head, bullets to the brain, or being burned, and scientists theorize radiation from a space probe returning from Venus may have caused the reanimations. Rescue centers promise safety, feeding hope amid the siege.
Ben devises a plan to obtain medical supplies for Karen and transport the group to a rescue center by refueling his truck at a pump on the farm. Ben, Tom, and Judy drive there, driving off ghouls with torches and Molotov cocktails. A spilled gas leak ignites, the truck explodes, and Tom and Judy are killed. Ben returns and breaks down the door when Harry refuses him entry.
The survivors scramble to figure out a way out. They pause their discussion to watch the 3 a.m. news update until the power cuts out. The ghouls breach the unlit house, and in the chaos, Harry grabs Ben’s gun but is disarmed and shot by Ben. Harry drags himself down to the cellar and dies beside his daughter.
Karen dies from her injuries, becomes a ghoul, and eats her father’s remains. Karen then fatally attacks her mother with a masonry trowel. Barbra fights to keep the ghouls at bay, but a reanimated Johnny drags her away. As the horde breaks in, Ben takes refuge in the cellar and shoots the ghouls that threaten the others.
In the morning, an armed posse arrives to dispatch the remaining ghouls. Awakened by their gunfire and sirens, Ben emerges from the cellar, but the rescuers mistake him for a ghoul and shoot him. His body is thrown onto a bonfire with the rest of the corpses.
