The story follows characters Ben (Duane Jones), Barbra (Judith O'Dea), and five others trapped in a rural farmhouse in Pennsylvania which is attacked by unnamed "living dead" monsters, drawing on earlier depictions in popular culture of zombies.
A French Army officer, Lieutenant Duvalier, has been separated from his unit and receives help from a mysterious woman. He follows her to the castle of Baron Von Lepp only to find that she is the Baron's wife who died 20 years ago.
A millionaire offers ten thousand dollars to five people who agree to be locked in a large, spooky, rented house overnight with he and his wife.
When a disease turns all of humanity into the living dead, the last man on earth becomes a reluctant vampire /zombie hunter.