A car pulls into a pathway and up to a vast mansion. A driver gets out and walks to the boot to get out a wheelchair. An Orderly comes out to open a rear door. Dr. Maxwell Kirshner (Ray Milland) is helped out of the car and put in a wheelchair. He gets wheeled up the steps and into the mansion.Kirshner asks if his experiment has been a success. He is told by the orderly that it has been. He is wheeled down the stairs into a basement where we see the experiment is in fact a two headed gorilla (Rick Baker) that Dr. Kirshner has in fact made. The experiment is to determine whether another head can survive on one single body. Dr Kirshner has done this because he hasn't got much longer to live and wants to transplant his still living head from his lifeless body and onto a another donor so that he may continue living and get back to working as the world's most successful surgeon. He approaches the bars of the cage that hold his new creature, even when told not to but he is unafraid. He says that the creature understands him and therefore will not hurt him.Dr Kirshner returns to his hospital institute to over look an operation done by his close friend and associate doctor named Phillip Desmond (Roger Perry). An onlooker asks why during the operation why he cant see more blood. He is told that both patients are hooked up to individual heart and lung machines and the blood is easily passed through plastic tubing all the time during the operation. Dr Kirshner returns back to the basement and his two headed gorilla to remove one of the heads from its body. A cage is opened to allow them to get inside from their original cage. The cage has no bottom layer so they use a table to place the cage on. Kirshner orders his assistants to sedate his creature but plans go awry when the creature is upset about the needle and knocks both the cage off of the table and Dr. Kirshner out of his wheelchair, hurting him severely. It then proceeds to smash up the lab and escapes. Kirshner tells the assistant to get the creature back as he doesn't have much time left to live. The creature runs away and into a supermarket where the assistants chase after it. The gorilla is found eating a banana in the fruit section of the supermarket. Kirshner hires a new doctor to help his friend with the transplant. Little does he realize that the new doctor is an African American and Kirshner hates African Americans. He is a bigot and a racist. He tells the new doctor that his services that were about to start are now no longer required because he doesn't want an African American doctor working anywhere near him or with him. He tells the African American doctor that he will be remembursed for his time and the original duration that he was supposed to be working for. The African American doctor whose name is Dr. Fred Williams (Don Marshall) takes great offence to this. Dr. Desmond sticks up for Dr. Williams saying whether he is African American or not, he is a damn good doctor.This disgusts Kirshner and he wheels himself out of the office. He returns once again back to the basement where he successfully removes the 2nd head of the creature. He calls his friend Dr Desmond and Desmond rushes over. He tells him he is ready for his own transplant to a healthy donor. Desmond is not sure about it until Kirshner tells him that the head that is now on the gorilla is in fact the 2nd head he put on. He had successfully removed the original gorillas head and replaced it with the 2nd transplanted one. Meanwhile on death row the convicts are told that if they donated their bodies to science, it will stop them getting the electric chair. One convict is lead to the chair which turns out to be an African American himself, a very big African American named Jack Moss (Roosevelt "Rosey" Gier). Just as they sit him in the chair, he decides to volunteer for the science experiment because he is innocent of the crime he was supposed to have committed and therefore he believes that in 30 days he will have freed himself of the accusation. The police, including Sergeant Hacker (Roger Gentry), escort Jack to the transplant center for this experiment they have been told about. The doctors are surprised to see a large African American being brought before them for this experiment knowing full well that when Kirshner wakes up, he isn't going to like what he sees. However the doctors work around the clock to transplant Dr Kirshner's head onto Jack's body.After the operation Kirshner wakes up and Desmond tells him that the operation was a success. Kirshner says he can feel the breath in his new lungs and that he can move his arm. Desmond tells him that they had no other choice but to transplant his head onto the African American's body. Kirshner says to Desmond "is this part of a joke?" Desmond tells him that he would not have lived another day if they hadn't of operated when they did.At that moment, Jack awakes and is freaked out by the fact that Kirshner's head is on his body. Kirshner tells him to shut up and rest so they can recuperate the energy to test drive his new body and try out his surgical procedures to become the world's greatest doctor again. Jack gets angry and try to get up from the table but Kirshner cries out for someone to sedate the Jack of the body, which Desmond does. Kirshner exhausted, tells Desmond that he couldn't control the Jack side of the body, he can only control the body if Jack is sedated or asleep. Kirshner is worried that Jack could harm his half of the body.Desmond tells him that he will keep the Jack side heavily sedated all the time while Kirshner regains the power to move the body. Leaving Kirshner to rest, Desmond meets up with Dr. Williams again and tells him he needs his help. Williams is reluctant at first because of Dr Kirshner but Desmond reassures him that his beliefs are not the same as Dr. Kirshner's and that his help is very much needed. Although Williams still doesn't know what has been asked of him, he is told by Desmond to go home and get some things together. Williams asks when he will find out what is going on in the room that is keeping Jack and Kirshner. Desmond tells him that he will find out in good time.Meanwhile a nurse (Britt Nilsson) comes to administer a sedation to Jack's side of the body. Jack tricks the nurse and wakes up, giving her the sedation needle instead by stabbing it into her bum. He tricks one of the cops outside the door to come in and knocks him unconscious. Grabbing the cops gun, he beats up the other cop and runs out of the building taking Williams with him/them. Williams drives the car under gunpoint by Jack and Desmond chases after them. Jack asks Williams if he can get rid of Kirshner's head off of his body. He tells Williams that if he won't help him then, as he will kill Kirshner and remove his head himself. Williams warns him that if he did that, he would be killing himself also. He also tells him that Kirshner's head can only be removed surgically if he wants a safe procedure.The police chase after Jack, Kirshner and Williams. Jack takes over driving and accidentally crashes the car and causes a flat tire. Williams sits with Kirshner and Jack beneath a tree and asks why Jack was on Death Row. Jack tells him that he was framed for a stick up that went wrong, a friend of his used a gun that Jack owned to knock off a store and he shot a cop. As the gun was Jack's and his prints were on the gun. Knowing that Jack was arrested for the murder, his friend ran away and Jack took the fall. Kirshner then tries to appeal to Williams by offering him the accolade of the transplant. Williams sees through his ploy and tells him that he insulted him and therefore would not accept his offer as it would mean that he would have to take off Jack's head from the body.All three of them run up a hill and find a motocross track. Jack watches as a motocross rider falls off his bike and Jack takes it and rides off round the motocross track with Kirshner and Williams riding also. Several bikes crash after seeing the two headed horror and soon the police are hot on their trail. Kirshner screams to Jack that he will get them all killed. Jack snaps back that he will get them out of this mess. Kirshner doesn't believe him and the bikes speeds towards a gap, a very deep gap which Jack easily jumps. The police cars chasing them, crash one after the other, some even land on each other. Luckily the cars are wrecked yet the cops are not injured.Jack rides the bike to his wife's house. Lila (Chelsea Brown) isn't that pleased to see him because of Kirshner's head is on his body. Jack asks his wife to kiss him, she almost does but is put off from the intimate moment by Kirshner's head. With a degree of sexual chemistry she then asks if he has two of everything meaning does he have two genitals. Jack laughs at this. Jack lays down to rest and Jack's wife Lila says she is gonna get dinner. Jack asks her to stay and he feels some sexual energy towards her. She is put off about this. Jack tells her that if Kirshner's head is putting her off that he will cover it with a pillow case. That doesn't change her mind and she walks off. Jack turns to Kirshner and tells him for interrupting his sexual activity that he has got to go.While Jack is sleeping Kirshner finds out that he can control the body almost fully. Kirshner is very happy about this. Jack, Kirshner, Williams and Lila sit down for dinner. Jack offers some to Kirshner who tells him he doesn't eat that kind of food. Lila says to Kirshner "What's the matter baby, dont you like soul food?". Kirshner replies with a bigot remark of "What's for pudding? Watermelon?" Jack tells Kirshner not to worry about the food as he is eating it not Kirshner. Lila strikes up a cigarette to which Kirshner asks for a cigarette. Lila gives him one and the smoke ends up coming out of Jack's mouth while he is eating. Disgusted by this, Jack takes the cigarette out of Kirshner's mouth and tells him not to smoke while he is eating. Lila asks what it will take to take Kirshner's head from Jack's body. Kirshner tells her that without a specially crafted surgical team, it is impossible to do the operation and both of them will die. Williams tells Kirshner that he is dead wrong about that, as the removal procedure is easily done without the aid of the surgical team.Williams drives to a medical warehouse to get what he needs for the operation. Frightened by what Williams has told him, Kirshner manages to take over Jack's body and starts playing around with his face. Jack asks him to stop it and Kirshner knocks out Jack by punching him in the face and then knocks over Williams too. Cornered by William, Kirshner calls Desmond for help in removing Jack's head so that he may live. Kirshner manages to get away and drives back to the basement in Kirshner's house, where he made and removed the gorilla's head. Before Kirshner can sedate Jack, Williams comes in and stops Kirshner. Williams then calls Desmond to get over to Kirshners' house as soon as possible. Desmond arrives with a nurse and an associate who find Kirshner detached head lying on the utensil table hooked up to a heart and lung machine which has his blood constantly pumping through the plastic tubes to keep him alive for a while. Kirshner calls to Desmond and begs for him to bring him another body.The film ends with Lila, Jack and Williams driving down the highway singing Oh Happy Day. They turn to each other and smile, they got rid of Kirshner and won the day.
Output: Question: What song do Lila, Jack, and Williams sing at the end of the movie?, Answer: Oh Happy Day