A wealthy industrialist hires the renowned hoax-buster Phillip Knight to prove that an island he plans to develop isn’t voodoo cursed. However, arriving on the island, Knight soon realizes that voodoo does exist when he discovers man-eating plants and a tribe of natives with bizarre powers.
The movie opens with title and credits running over mist and a voodoo doll with a spear in its head. Cut to a model of a proposed hotel resort, namely the Paradise Carlton.We are in Hawaii and Phillip Knight (Boris Karloff) takes the pulse of a man, Mitchell (Glenn Dixon) who appears to be in a trance. Dr. Wilding (Herbert Patterson) explains that, "There's nothing organically wrong with him. He's probably in a plenary trance under a mental block." Howard Carlton (Owen Cunningham) owns the island on which the resort is planned, and Mitchell was on the first expedition to site the hotel. He was one of a four-man survey team of architects and engineers sent to bring back a report. They never returned, except Mitchell. "He was found on a boat beached on some other island fifty miles away," Carlton explains. Barney Finch (Murvyn Vye) is Carlton's assistant. He gives his boss a drink. Knight is a debunk artist with his own television show. Knight is convinced Carlton is amping up Mitchell's condition to help advertise his new hotel, "to cover the island with a spell of voodoo." Carlton wants Knight to visit the island and dispel the rumors and myth of voodoo. He tells Knight there are no strings attached. It is settled, but as for the passenger manifest, that is hammered out next. Carlton tells Knight he wants to send Winter, his chief designer, and Barney Finch. Knight, of course, wants his assistant Sarah Adams to accompany him. He also demands Mitchell attend, and of course his physician, Dr. Wilding. Barney confirms six passengers. Mitchell just stares straight ahead. When Barney tells the dispatcher Mitchell is coming along, the telephone line goes dead. At that, the birds in a cage, parakeets, begin squawking. The live plants on the model wilt and die and begin dripping blood.At the Lihue airport, Claire Winter is paged. His pilot tells Knight, "We're clear to take off in thirty minutes." Claire Winter (Jean Engstrom) talks to Sarah Adams (Beverly Tyler) in the lounge. "All that work. I think its wicked," Claire tells Adams while she offers her a cigarette and a drink. Adams politely refuses. Barney takes Claire's invitation and they head for the bar. While subtle, Claire obviously prefers the company of women over men. The plane for the Knight party is ready to depart. Dr. Fielding takes Mitchell by the arm and helps him aboard. They depart in a Beechcraft Model 18 twin-engine airplane.Weather Station 4 gets a call on its radio, "N5621Victor, calling Weather Station Four." The Radio Dispatcher (uncredited Adam West) responds. But despite many calls, the aircraft can't pick up the transmission. They claim the weather is bad, but the ground station indicates no weather disturbance within five-hundred miles. The pilot announces they are landing. They land on the island to clear skies and unlimited visibility. The party exits the plane.Adams is typing notes while Barney naps in the lounge of the weather station. The pilot is testing the radio by calling Wake Island. Claire is sleeping on a cot and Knight is napping in a chair. The doctor is nodding off, but his patient, Mitchell just sits and stares, unblinking. The pilot and co-pilot continue to test the radio and chit chat with the weather station personnel. The hum of the radio receiver seems to be having an effect on Mitchell. He stands up and stumbles across the room towards Adams. She screams and Mitchell collapses. He is moved to the cot and Dr. Wilding checks his blood pressure. It keeps dropping. The radio finally works and Mitchell's blood pressure returns to normal. They board the aircraft and depart. They land on an island and are met by Matthew Gunn (Rhodes Reason). He is happy to see women, and particularly Miss Winter. He is not happy to see Mitchell, as his boss will be very upset. They board two Jeeps for the ride four miles to the other side of the island.Martin Schuyler (Elisha Cook, Jr.) is outside tending to some plants. He adjusts his tie and walks over to greet his guests. He is visibly upset when he sees Mitchell. "What's he doing here? This man's not in his mind. He's among the dead." Knight and Finch persuade Schuyler to allow Mitchell to stay.That evening Adams steps out onto the porch. Claire joins her to talk. She makes a pass at Adams. Uncomfortable, Adams proclaims, "I'm going for a walk." She bumps into Gunn and rushes off. Gunn tries his luck with Claire. She brushes him off also. Knight and Finch arrange for a boat from Schuyler. It requires a lot of cash to persuade the superstitious man. Gunn tells Knight that the island they propose to visit has a reputation. Schuyler agrees to all the arrangements and is happy with the cash settlement. Of course, he fobs all the work off to Gunn then leaves the room. He returns almost immediately and says, "Mitchell! He's gone. Wilding's on the bed." The doctor is confused, he was reading in a chair and then nothing. Hearing the commotion, Knight enters the room and directs them to follow him outside. Mitchell is walking to the dock. He passes Claire and Adams on his way. They run back to the hotel and encounter the search party out to find Mitchell. Mitchell crawls aboard a boat and collapses, eyes finally shut. They board and Dr. Wilding checks his pulse. He pronounces him dead.The next morning, Schuyler is out and about and in an excellent mood. He has money and Mitchell is out of the picture. He chats with Claire and explains that all his troubles are over. He is giddy about his new partnership with the Carlton Empire. Mitchell is flown back to Hawaii for an autopsy. Knight predicts the autopsy will reveal, "That he was scared to death." The six board the boat and Gunn finds an Uhuanga bag. Inside is a piece of paper–a death wish. Knight tells Gunn there should be six, one for each of them, and ashes. Knight tosses the bag overboard and they depart. After a few hours at sea they spot the island. The boat engine fails. Gunn tires to start it back up with no luck. After considerable work in the engine room, he discovers an insect plugging the fuel line. Gunn reassembles the engine, but the boat still won't start. They drift over to the island.By the next morning, they drift close enough to walk ashore. The walk down the beach to a clearing and Knight finds something shining in the jungle. They investigate and spot a land surveyor's marker. Something falls from a tree and almost hits Adams. A large coconut land crab scurries towards them. They head into the jungle, but are spotted by two natives hiding in the foliage. They hack their way through the jungle growth. They find a surveyor's transit. Knight looks through it and spots a small clearing in the distance. They walk towards it thinking it may have been a camp. Knight finds evidence this was the first party's camp–tent pegs and ashes. Finch finds a spoon with the Carlton crest stamped on it. They decide to walk back to the boat to get supplies. They leave the women in camp. The women build a fire. The men return with bad news. No supplies. All the food was rotten with maggots. They bed down for the night and again are under the watchful eye of some natives.Adams is unable to sleep and walks over to talk to Gunn. They trade insults. Gunn apologizes, but they continue to bicker. The next morning Adams goes out with her camera to get some pictures for her boss. Claire decides she needs to do some work. She wanders off and finds a lagoon with a waterfall. It looks so cool and inviting she decides to go for a swim. A strange looking plant floats on the surface of the lagoon. Claire's splashing and swimming activates the plants long, thick, tube-shaped leaves. She swims for shore. The plant encircles her and wraps itself around her body like a series of pythons. It constricts around her chest and neck squeezing the life out of her. Her screams bring the rest of the party but it is too late. Knight pronounces the plants, "Carnivorous Plants. Throwbacks to the Paleocene epoch nearly fifteen million years ago." Knight is convinced they are being drawn deeper into the jungle for a reason. Before departing, Finch, Knight and Schuyler bury Claire. Gunn takes Adams away. Gunn tells Adams, "I had a boat blown out from under me around one of these islands during the war. I lived. Nobody else lived." A land based carnivorous plant is weaving back and forth ready to strike Adams. It attaches itself to her and Gunn shoots it. He then takes a machete to hack at the roots. Knight, Finch, and Schuyler arrive to help. They free her and continue their trek deeper into the jungle.They bed down for the night. Gunn and Adams reconcile. They kiss. The next morning Finch wakes early. He sees a carnivorous plant just before it strikes him. It freaks him out. He wanders for a while through the jungle and hears children playing. Two small native girls are running through the brush near a clearing. He hides not wanting to be discovered. The smallest of the two falls into a large plant that immediately closes up around her suffocating and consuming her. This is too much for Finch. He loses his mind and becomes like Mitchell.Adams wakes and screams. A man with a machete stands over her. A small group of natives enter the camp and surround them. Schuyler pulls a gun but Knight stops him before he can fire. They are marched through the jungle towards the native village. They cross a bridge constructed of wood and vines over a river. In a hut the doll likenesses of the previous expeditionary party sits on a shelf. All four dolls have arrows in their hearts or heads. The Native Chief (Friedrich von Ledebur) tells them that over fifty years before he led a band of people to the island to avoid the crush of civilization. A native leads Finch to join the rest of his colleagues. Upon seeing Finch, Knight observes, "Same as Mitchell." Knight, speaking for the group and not entirely sincerely, tells the Chief, "I understand. Have no fear. Your secret will be safe." Schuyler scuttles the gambit by telling Knight and the Chief, "I'll not be robbed out of my part of this island." The Chief orders them removed, even Finch. In a hut for the night, they tie their wrists together with rope to remain together. If one of them is taken, it will wake the others.The next morning, a doll reclines between Knight and Gunn where Schuyler was. It is tied to Knight and Gunn with rope. Finch is sitting up and staring. Knight cuts them all loose. Knight leaves the hut and discovers the village is deserted. He calls out to Schuyler and finds him on the foot bridge. Schuyler acts strangely and moves backwards on the bridge, unsteady on his feet. He gets the bridge undulating. He sees the doll of his own image, screams, and falls off the bridge into the river below. He sinks to the bottom. Knight picks up Schuyler's doll and it now has an arrow through its heart. The Chief appears. Knight tells him he was lying to him earlier. He admits that he does believe. Gunn notices the doll that was tied to his wrist is missing when Knight hands it to him. The Chief tells them, "I think all of you may go now." Gunn takes Adams across the bridge. Knight accompanies Finch across the bridge. The Chief tells knight their troubles are not over. There are still the plants, but he has men waiting to lead them back to their boat. We close with Knight leading Finch and following Gunn and Adams through the jungle.