For Dr. Robert Morgan (Price), each day in 1968 is the same: he gets up, gets his weapons, and then goes vampire hunting. Morgan lives in a world where everyone else has contracted a sickness that has made them into vampires and undead who are repulsed by garlic, afraid of mirrors, and unable to withstand sunlight. Fortunately, they are weak and stupid, but they would kill Morgan if they could. Morgan isolates himself in his home at night and burns the corpses of as many vampires as he can during the day. According to a flashback scene, Morgan's wife and daughter had died of the plague three years prior, before the general population was aware that the dead might come back to life. Morgan buried his wife without the authorities knowing, rather than transporting her to the same public burn pit where his daughter's body was dumped. Morgan realized he needed to use a wooden stake to murder the plague victims after his wife came back to their house and attacked him. Because he was bitten by an infected vampire bat when stationed in Panama, which injected his blood with a diluted form of the plague, Morgan surmises that he is resistant to the germs. A dog shows up in the neighborhood one day. Morgan, who is in dire need of company, runs after the dog but fails to capture it. After a while, the injured dog shows up at Morgan's house. Anticipating visitors for the first time in three years, he brings the dog inside and tends to its injuries. Nevertheless, he soon learns that it has also contracted the disease. After impaling the dog with a wooden stake, Morgan is subsequently seen burying it. In the distance, Morgan sees a woman after burying the dog. Ruth, the woman, flees from Morgan because she is immediately afraid of him. Despite his misgivings about her character, Morgan persuades her to come back to his house. Morgan claims to have a weak stomach, but when he waves garlic in Ruth's face, she gets sick. When Morgan finds Ruth trying to inject herself with a blood and vaccination mixture that prevents the disease, it confirms his belief that she is infected. Ruth pulls a gun on Morgan at first, but then hands it over to him. Ruth then informs him that she was assigned to spy on Morgan and that she is among a group of people who are similarly affected but receiving treatment. When the vaccine wears off, the virus retakes control of the body, but while the medicine is in the bloodstream, the person can function properly. Ruth clarifies that many of the vampires Morgan killed were technically still alive and that her people are preparing to restore society while they eliminate the remaining vampires. Ruth implores Morgan to run, but he uses irrationally. Morgan gives Ruth a transfusion of his own blood while she is asleep. She is instantly cured, giving Morgan hope that they can all work together to heal the rest of her people. But a few moments later, Ruth's people launch an assault. As the assailants murder the vampires gathering around his house, Morgan grabs the revolver and leaves. Morgan is spotted and pursued by Ruth's people. Along the way, he takes up tear gas grenades from an armory at a police station and engages them in shooting. As his assailants are somewhat delayed by the tear gas, Morgan is shot and takes cover in a church. Morgan's assailants ultimately impale him on the altar with a spear, despite Ruth's pleas for him to be spared. As he draws his final breath, Morgan calls his assailants "freaks" and proclaims himself to be the last real man alive.