Robert Morgan (Vincent Price), a scientist, is the sole survivor of an apocalyptic plague unleashed upon the entire earth. Facing a maddening situation, it is made worse by the bloodthirsty zombie like vampires who crave his blood for survival. The year is 1968, and Morgan begins his day quite unlike others have in the past. He secures his home, gathers the weapons necessary to destroy the awaiting blood suckers who will soon rule the night, and ponders the world in which he now exists. These undead creatures cannot brave the sunlight, are repelled by garlic, and fear their reflection in the mirror. They would kill Morgan if not for the fact that they are weak and simple-minded. After collecting the vampiric dead, Morgan sets them ablaze in a funeral pyre.
We are guided through a flashback three years prior telling of how Morgans wife and daughter succumbed to the outbreak before all knowledge of its ramifications were understood. Instead of bringing his wife’s body to the public burning pit where his daughter had been placed, he buried his wife separately without the authorities consent, only to have her return to try to kill him. It is then that he comes to realize they must be destroyed with a wooden stake. After some reflection, he comes to the theory that he is immune to this plague as a result of having been bitten by a vampire bat while stationed in Panama, which introduced a resistance in his blood. While on his daily rounds, Morgan stumbles upon a woman in the distance named Ruth Collins (Franca Bettoia). She is terrified but is convinced to return to the scientists home, though he is still suspicious of her. In an attempt to discover her true nature, garlic is waved before her, causing her to be moved by it but claims herself to merely have a weak stomach. However, when Morgan’s suspicions are confirmed discovering her injecting herself with a vaccine that she tells him holds the disease at bay, she confesses to him that she is with a group of people who are infected but under treatment and was sent to spy on him. The vaccine must be administered on a continuing basis or the disease will overrun them. They planned to kill the vampires and rebuild a society free from the danger. While ruth slept, Morgan transfuses his blood into her, curing her of her malady in hopes of doing the same for the rest. And in a sudden attack, Ruth’s people place the entire area under siege killing the vampires surrounding Morgan’s home. Morgan grabbing his gun flees his dwelling. Chased and pursued, he is involved in an exchange of gunfire and is wounded. Retreating to a local church. Despite Ruth’s pleas to let him live, his pursuers impale him on the altar with a spear. With his last dying breaths he denounces them as freaks, decreeing himself as the last true man on earth.