Dr. Hess Green, played by Duane Jones, is an affluent African American anthropologist who dedicates his research to studying the ancient Myrthians, a legendary African civilization known for their blood-drinking practices. His story takes a dark turn one night when he stays at his opulent mansion, which is richly adorned with striking African art. During his stay, his unstable assistant, Bill Gunn as George Meda, threatens to end his life in a desperate act of despair. Green manages to calm him down, but later that very night, Meda unexpectedly attacks Green, stabbing him with a ceremonial Myrthian dagger before taking his own life. Green survives this brutal assault but, in a moment of dark curiosity, drinks Meda's blood upon discovering his body. This act transforms Green into a vampire, granting him immortality and an insatiable hunger for fresh blood.
To sustain his new undead existence, Green initially steals blood bags from a nearby medical office, but he soon realizes that this isn't enough, and he begins to seek out living victims to quench his thirst. His quest for blood introduces him to Ganja Meda, played by Marlene Clark, who is the estranged wife of George Meda. She arrives at Green's mansion searching for her husband and, despite the shocking discovery of his lifeless body stored in Green’s wine cellar, she becomes involved with Green. The two quickly develop a romantic connection, and Ganja moves into Green's luxurious home. She is initially taken aback when she discovers her husband's corpse but, after some time, accepts her new reality and agrees to marry Green. As part of her transformation into a vampire, Ganja is turned by Green, which leaves her initially horrified but gradually learning how to cope with her new immortal existence.
The story deepens as Green introduces her to the darker aspects of vampirism. Together, they target new victims, with Green bringing home a young man whom Ganja seduces and kills, then disposing of his body in a field on Green's estate. This cycle of violence becomes routine as the vampires grapple with their desires and the moral implications of their actions. However, Green begins to grow disillusioned with his eternal life, feeling a yearning for redemption and a return to his faith. He seeks solace in the Christian church led by his chauffeur, Sam Waymon, Reverend Luther Williams. Ultimately, Green chooses to end his life, placing himself in front of a cross where he kills himself, seeking peace in faith.
Despite Green's death, Ganja survives, hinting at her continued existence as a vampire. The film concludes with a haunting scene: the young man Ganja previously murdered emerges alive from the water, completely naked, and runs toward her, leaping over the lifeless body of Archie, Green's servant, played by Leonard Jackson. This ending leaves viewers with an unsettling sense of the persistence of the vampire curse beyond Green’s demise, emphasizing themes of eternal life, moral conflict, and the darkness that lurks beneath human civilization.
