The title and credits are shown over an African village of native dancers. The opening scene shows a native girl, Zuranda (Jean Davis) participating in a ritual and placed on a table. A voodoo doll is placed on her chest. A chicken is waved over her and placed on her stomach and killed. Participating in the ritual is Dr. Roland Gerard (Tom Conway). He draws a sample of her blood.
In the doctor's hut, Bobo, the houseboy (Otis Greene) enters and opens the blinds. He startles Susan Gerard (Mary Ellen Kay), the doctor's wife. Susan tries to bribe Bobo to help her escape her husband, but he fears the doctor's wrath. The hut is like a prison with bars on all the windows. Outside sits a guard, Gander (Emmett E. Smith). When Susan gets too close to the bars she gets a little too close to Gander's spear and she retreats inside. The ritual continues with Dr. Gerard and Chaka, the Witch Doctor (Martin Wilkins).
In a bar, Rick Brady (Lance Fuller) and Marilyn Blanchard (Marla English) wait to approach a potential business partner. The bartender, Marcel Chateau (Paul Dubov) assists them in their scheme. Marilyn cozies up to Harry West (Norman Willis) at his table. They know and dislike each other, but they agree to a business venture. Marilyn tells Harry she intends to marry Rick. Rick and Marilyn leave the table after exchanging a few more barbs with Harry. They walk back to the bar and annoy Marcel and have a drink. She tells Marcel she's going to Harry's room and to distract their "business partner." Marcel tells Yvette, the singer (Giselle DArc) to keep Harry occupied with a song. Marcel helps himself to his own product. Rick and Marilyn rifle Harry's room. They are looking for a map of the location of a tribe that has enormous amounts of gold and jewels. Harry notices his "business partners" have left. For $5 Marcel sells Harry a gun. Harry is unaware his weapon doesn't work, but Marilyn does. Harry returns to his room to find Rick and Marilyn examining a gold statue studded with diamonds and rubies. Harry's gun malfunctions, but Marilyn's works fine and she uses it to kill Harry. They continue to search Harry's room. It seems Harry had made arrangements before his untimely death to secure the services of a guide to find the tribe and collect the gold and jewels. That much Rick and Marilyn know.
At the ritual, the girl's feet change. She changes into some kind of blond hairy creature, but we don't get a very good look. The witch doctor tells Dr. Gerard the change is only temporary. Zuranda is the daughter of the priest in the next village, so the tribe is responsible for her safety. Gerard wants to take Zuranda with him, but Chaka objects. Gerard finally convinces Chaka to let her leave, but just about that time Zuranda changes back to a native girl. Gerard wants the change to be permanent.
Marcel comes to Harry's room to tell Rick and Marilyn that Harry's funeral is over. For a percentage Marcel arranges such things. He informs Rick and Marilyn there is a considerable fee due and payable. They are waiting for the guide, and since it was arranged by mail, Rick will impersonate Harry. The guide, Ted Bronson (Mike Connors, credited at Touch Connors) arrives at the bar and meets Marilyn. He is suspicious of her motives, but he needs the money.
The next day they plan their trip. The three start their trek through the jungle complete with bearers. They decide to make camp just outside the voodoo territory. Gerard has returned to his lab with Zuranda. She screams which upsets his wife back in the hut. Susan enters the lab, against standing orders. Before he can send Susan back to her room, he informs his wife, "I'm using her to create a new being, not man, not beast, but a combination of the best of each. When I'm finished we'll take her back to the States with us. We'll shatter the very foundations of Science." Susans reply is terse, "You're insane." Gerard reminds her if she tries to escape he'll kill her. Zuranda again transforms. She has claws like a panther. The creature (Paul Blaisdell) is directed telepathically to go to the village. It destroys a hut and chases the couple with the baby inside off into the jungle. But Zuranda has serious qualms about harming anyone, and transforms back into her human form.
Resting in the camp, Marilyn asks Ted about voodoo. Marilyn is drawn to the drums and tells Ted she's going to the north country. Ted informs her it will be without him. The next day Gerard approaches the village and is stopped by the natives until Chaka intervenes. Chaka confronts Gerard with the evidence he made Zuranda attack her own village. Chaka wants her back and Gerard agrees. He is told she will never kill because it is not in her nature to do so. Gerard departs. Ted and Rick get into a fight over Rick's trying to shoot a native scout. Ted is victorious and takes Rick's rifle. But the native village now knows of the white man's presence. Gerard takes his wife down to the lab to see Zuranda. Susan thinks she's dead. But Gerard explains that she is between life and death--a state of pre-transformation. Gerard smears blood on a doll and then tells Zuranda to get up and walk around the room. Zuranda complies. He injects her with a substance that turns her skin into armor plating. Gerard fires a gun at Zuranda and the bullets bounce off. Even acid has no effect when poured on her leg. Susan accuses her husband of being crazy and gets a slap across the face for it.
Ted confesses to Marilyn that he thought she was poison the minute they met, but took the job because he needed the money. He asks for a straight answer, what are they looking for? She makes him a bargain--a 50/50 deal. She wants gold and badly. He agrees to take her as far as Bandaleya. She pulls a gun on Ted and takes his gun. She informs Ted he's going with her and Rick.
When Bobo tries to take a message from Susan to the party approaching he is killed by Gander. When Ted tries to escape, Marilyn ties him up. Rick leaves looking for the village. Gerard is looking for Ted, Rick, and Marilyn. He has Zuranda with him in her transformed state. Gerard finds the camp and directs Zuranda to kill, but she is unable and retreats and transforms back into human form. Gerard admits that Chaka was right, he can't make her kill. He sends her back to her village. Rick finds the markings on the native totem pole which confirms they have the correct village. Ricks accosts Zuranda. She screams and bites Rick. He hits her and kills her. He walks back to camp and wakes Marilyn. He tells her they've found the village. Gerard and Chaka find Zuranda's body. Chaka informs Gerard, "White man die for this." Gerard agrees, until Chaka informs him that all white men, "You too." They go to the camp and capture Rick, Ted, and Marilyn. They want the one who killed Zuranda. Marilyn rats out Rick. The bite on his hand is the evidence. Chaka insists Rick be executed by a white man, so Marilyn shoots Rick twice killing him. Dr. Gerard cuts Ted loose and they agree to stay with Gerard for a few days until things calm down with the villagers. Of course, Gerard has plans. Marilyn tells Gerard, "It's lucky meeting up with you. I've got a hunch I can use you in my business." Smirking uncontrollably, Gerard slyly replies, "I'm almost positive that I can use you in mine." They go back to Gerard's hut. Gerard takes Marilyn on a tour of the lab. He surmises, correctly, that gold is Marilyn's real interest in the village. He tells her he will arrange to make her a priestess. "Then you can have anything you'd like." Susan is locked in her room, but she has a rifle. She leaves her room and Ted notices her. They talk and she returns to her room. Gander keeps Ted inside the hut.
At the village, they prepare for another ritual. Gerard and Marilyn arrive. Gerard convinces Chaka to use Marilyn for the ritual. They return the next day, and Marilyn is dressed in native garb for the ritual. Gander falls asleep and Ted goes to the lab. He checks around then leaves to get Susan in her room. Gander wakes and goes outside. He hears Susan and Ted talking. He captures Ted. Chaka and Gerard work on Marilyn. She transforms into the monster. Chaka pulls a ritual knife on Gerard so he takes Marilyn back to his hut after she transforms back into human form. Gerard takes Gander away from guarding Ted for a little task. Unguarded, Ted goes to see Susan. He grabs a knife and departs. In the lab, Gerard preps Marilyn for her new role as his monster/slave. Ted bolts the hut with Gander in hot pursuit. Just before Susan can escape, Gerard arrives with his monster. Susan shoots it with no effect. The monster picks Susan up and takes her in the direction of the village. Ted manages to kill Gander. Gerard escorts his wife the final distance to Chaka as the white sacrifice Chaka demands.
Ted finds traces of Susan at the hut and hears Susan's screams at the village. He is captured by natives and brought to the village to be added to the sacrifice pile. Susan and Ted are tied up by next to a volcanic steam vent. Gerard calls his monster to come get her gold. Gerard is led away to be tied up with Ted and Susan. Ted and Susan manage to slip their ropes and get away as the monster attacks the village. Gerard orders the monster to kill Chaka--He is thrown into the pit. The monster discovers that all the ritual vessels are made of clay, not gold. Gerard informs the monster that the only gold item was the idol that went into the pit with Chaka. The monster feels betrayed and chokes Gerard. The monster returns to human form, now Marilyn. She sees the golden idol near the pit and approaches it. She bends down to retrieve it and falls into the pit, screaming. Ted and Susan return to the lab and mix up a couple of molotov cocktails. They use them to scare the natives and escape.
At the bar, Marcel and Yvette are rolling a drunk for his wallet. Yvette gets her cut. Ted and Susan arrive just in time for the bus to town. Marcel asks about Marilyn and Rick and is told they are dead. Marcel comments, "Her friend perhaps is dead, but not Marilyn. I have a feeling that one still lives." We close at the pit/steam vent as the creature crawls out.