Steve Adams, a theology student, begins to suspect he may be a vampire after a series of blood-draining murders in his town. A detective in the small town has hired Inspector Butterfield, a bumbling expert from England, to be his assistant in the investigation of the 27 murders. While walking down the sidewalk, Steve is approached by a couple on a motorcycle and asks them to come to church with him. They laugh and try to rob him at knife point, but he suddenly transforms into a vampire, and hypnotizes them to drive off a cliff. At the police station, Butterfield explains how he had tracked down and defeated Dracula with a wooden stake and that these murders fit the same profile, but the detective tells him to stop talking and get to work. The two meet for a drink with Steve, who turns out to be the detective's best friend and has always loved eating peanuts without shelling them.
Rev. Adams, Deafula's father, the preacher, contends with a worsening heart condition and can no longer provide Steve with the monthly blood transfusions he needs to survive. There is a flashback showing that Steve's mother died giving birth, a doctor diagnosed the baby with a blood disease, and the mother's best friend Amy mysteriously disappeared. As Steve and his father are driving, Steve starts acting strange and the preacher asks if he's feeling okay. Steve pulls over and runs away to puke. The preacher tries to run after him, but has a heart attack and falls to the ground. Deeper in the woods, Steve sees a young couple kissing, and murders them both. Steve finds his father lying on the ground, and the preacher manages to give him a letter from Amy before passing away.
When the detectives show up, Butterfield finds the other two bodies in the woods and tries to question Steve, but the detective won't allow him to interrogate his best friend. Before leaving the crime scene, Butterfield looks closely for evidence.
Steve follows the letter's instructions to Amy's house, where he's greeted by her servant Zork who has no hands. She explains to Steve that she was there at his birth, and knows that his mother had been bitten by Dracula while she was pregnant. She has a magic ring which disappears each time Steve transforms into a vampire, and reappears when he returns to normal. Zork hypnotizes Steve, and Amy tells him that he must go to the museum where Dracula is buried.
In a deep cavern below the museum, he finds Dracula inside a coffin, with a stake in his heart. He removes the stake, and Dracula is resurrected, along with Steve's mother. Dracula tries to hypnotize Steve, but he manages to kill Dracula. At that instant, Dracula and the mother vanish into smoke.
Steve gives a sermon for his father, but cringes when he sees a girl accidentally prick her finger in one of the pews. After the funeral, Butterfield arrests Steve, explaining that he found peanut shells in the vomit near the most recent crime scene, and citing the fact that Steve cringed in response to the finger pricking. Steve asks for a few minutes to pray before going to jail, and he gives a rousing prayer to God asking for forgiveness. He touches the magic ring to a crucifix, which kills Amy and replaces Zork's hands. Steve dies on the floor of the church.
