While visiting their father's grave, a sister and brother, Barbara and Johnny, are attacked by a strange, disheveled man. Leaving the unconscious Johnny behind, Barbara flees to a nearby farmhouse and discovers a horribly mutilated corpse. Meanwhile, the strange man has been joined by several other ghoulish figures who are trying to help him break into the farmhouse. Suddenly, Ben, a young black salesman also seeking refuge, appears and fights his way past them into the house. While barricading the windows and doors, he explains to Barbara that a mutation resulting from radiation has caused the dead to arise and devour the living. Ben learns from a television report that fire frightens the ghouls and that they can be killed by a bullet or blow to the brain. Barbara and Ben then find that they are not alone in the farmhouse: in the basement are teenaged couple Judy and Tom as well as married couple Helen and Harry and their young daughter, Karen. Unknown to Helen and Harry, Karen has been injured by the ghouls and is slowly acquiring their disease. Ben improvises a plan to help Tom and Judy escape; but they panic and die in a fire and are devoured by the zombies. The ghouls finally burst through the barricades, and Ben accidentally shoots Harry; Barbara is dragged away by her brother Johnny, who has become a ghoul; and Helen is murdered and eaten by her infected daughter. By morning, when the living have succeeded in suppressing the dead, only Ben has survived by barricading himself in the basement of the farmhouse. But he is mistaken for a ghoul and shot through the head when he bursts out to greet a posse sent to destroy the zombies.