Mamawalde (William Marshall) is an African prince who, along with his wife, Luva, is invited to Dracula's castle, to close the slave trade. But Dracula, a racist, has no intention of doing this. He traps the woman and transforms Mamawale into "Blacula" and imprisons him in a coffin in a hidden room. Two hundred years later two gay antique dealers from Los Angeles purchase items from the castle, including this coffin. One of these guys is white, one is African-American. Blacula awakens when one of the guys cuts himself--and brutally kills them, like an animal, before returning to his coffin. When he is in "vampire mode" he becomes hairier, sort of like Mr. Hyde.
At the funeral home, the black antique dealer's corpse begins to awaken. Blacula makes an appearance--and sees that one of the mourners looks exactly like his dead bride, Luva. Her name in this life is Tina. Her sister Michelle's brother is Dr. Gordon Thomas, who finds the neck wounds suspicious. That night, Blacula follows Tina down the street and scares the crap out of her because she thinks he's a stalker. She returns to her apartment and locks the door--and Mamawalde encounters a woman taxi driver and drinks her blood.
At a night club Mamawalde runs into Tina and returns her purse--and she invites him to her table, where her sister Michelle and Dr Thomas are also sitting. He explains to her how she strongly resembles his late wife and apologizes for frightening her the night before. She accepts all this--and becomes interested in him. A woman takes a picture of them--and later on, while she is developing the photos, sees that he is not in any of the pictures. He shows up and drains her blood as well. Afterwards, Mamawalde pays Tina a visit and tells her his story, of how he travelled Europe to stop the slave trade and how Dracula cursed him. He tells her that she is Luva, reincarnated, and wants her to join him in a life of the undead. But she must come to him freely, not by force. She's confused.
The funeral director calls Dr. Thomas and informs him that the body has disappeared. This is around the same time the taxi cab woman's corpse appears at the morgue, punctures in her neck. Thomas ends up going to the other antique dealer's grave and digs it up--and the guy springs out, a vicious vampire. He kills him with a shovel. He then calls the coroner and tells him to lock up the body--but it's too late. She has resurrected and attacks him in slow-motion.
Mamawalde and Tina have sex.
Thomas suspects he's a vampire--and even convinces the police captain--and they go to an abandoned warehouse where there are lots of newly made vampires. They throw molatov cocktails and set the place on fire. Blacula shows up after they narrowly escape and tells them he has hidden his coffin elsewhere. They want Luva to help them capture him but she's in love with him. But she reluctantly agrees to help.
In the end, she accidently gets shot by the police and is dying. Blacula turns her into a vampire and they find her and stake her as she screams. He's pissed--and when he sees that she is dead, he's devasated. Instead of killing Thomas he turns and walks out into the street, in broad daylight, where the sun disintegrates him into a skeleton.
But wait, he's not completely dead, as we find out in SCREAM, BLACULA, SCREAM (1973).
By today's standards this movie may come off a bit cheesy but it successfully presents all the classic vampire mythology and drama in a unique 70's way. Recommended.