When the Mama Loa of a voodoo cult dies, there is an argument over who will succeed her. When the popular vote is for Lisa Fortier [Pam Grier], cult member Willis [Richard Lawson] vows revenge. In a misguided attempt to gain power over his enemies, he acquires the bones of Prince Mamuwalde, aka Blacula [William Marshall], and resurrects the vampire. Blacula vampirizes Willis and places him under his control.
As vampirism spreads among the circle of friends and cult members, Blacula takes an interest in Lisa after meeting her at a party thrown by Lisa's love interest, Justin [Don Mitchell]. Justin is a collector of African art, and Mamuwalde sees, among other artifacts, a necklace once worn by his beloved wife, Luva. Blacula is interested in Lisa because he believes she can lift the curse upon him by casting a voodoo spell and performing an exorcism. Justin begins to work with the police in order to solve the recent spate of bloodless corpses and disappearing victims, and quickly makes the connection to Mamuwalde.
Lisa is, at first, sympathetic to Mamuwalde's situation and agrees to go through with the exorcism, but they are interrupted by Justin and the policemen he has brought with him to eradicate the vampire. Infuriated that the rite of exorcism was interrupted, especially since it seemed to be working, Blacula goes on a rampage and begins to kill the policemen, eventually threatening Justin. Lisa is horrified and realizes she must stop Blacula. The film ends ambiguously as Lisa seizes the voodoo doll of Blacula, which she created for their exorcism, and plunges a wooden arrow into its heart over and over, while Blacula screams in agony.