In Los Angeles, California, Dr. Michael Hfuhruhurr, the world’s greatest brain surgeon, performs a gratuitous operation to demonstrate his technique to Olsen, a journalist who is conducting an interview. Afterward, they drive through an affluent neighborhood while Michael explains how his fascination with slime drew him to brain surgery. Nearby, as elderly millionaire Timon Creswell is dying of a heart attack, he informs his evil mistress, Dolores Benedict, that she has been disinherited. She runs into the path of Michael’s car and sustains a serious head injury. As Dolores lies unconscious in the street, the recently widowed Michael is transfixed by her beauty and becomes infatuated. Michael insists on performing Dolores’ operation, and employs his innovative “cranial screw-top” technique, which obviates the need for cutting or drilling the skull. When Dolores regains consciousness, she entices Michael by sucking his finger. Her continued advances prompt Michael to consult the spirit of his late wife, Rebecca, asking for a sign if she disapproves of his love for Dolores. Rebecca’s portrait spins on the wall as the house shakes and a disembodied voice emphatically repeats the word “no.” Michael is oblivious to the warning and marries Dolores in her hospital room. When Dolores is discharged, Michael carries her over the threshold of his home, wishing to prolong the moment, which he does until morning. Dolores’ recovery is slow and she complains of constant headaches, delaying the consummation of the marriage. Michael is driven to the edge of insanity from sexual frustration, unaware that Dolores is having an affair with Juan, a virile young gardener. Michael accepts an invitation to lecture on brain transplantation at the Austria Institute of Craniology in Vienna, hoping that the change of scenery will improve his wife’s libido. Shortly after arriving in Vienna with Dolores, Michael is escorted to the institute by Dr. Conrad, who warns him of the Elevator Killer, the serial murderer who took the life of renowned craniologist Dr. Schlermie Beckerman. At the conclusion of his lecture, Michael is approached by Dr. Alfred Necessiter, who believes his pioneering work in mind transference will soon render Michael’s brain transplant methods obsolete. Necessiter brings Michael to his home laboratory, a cavernous medieval castle housed inside a modern condominium building. In the laboratory are numerous preserved brains, all from victims of the Elevator Killer, who injects his quarry in the buttocks with window cleaner, allowing the brain to continue functioning for a time after the body has died. Necessiter invites Michael and his wife to dinner that night, promising to introduce them to the reanimated Dr. Beckerman. Michael returns to his hotel room to find Dolores being fondled by a stranger and declares an end to the marriage. However, after Michael leaves the room, Dolores intercepts a telephone call from attorney James Gladstone, informing her that Michael has inherited $15 million from his deceased step-grandmother. Later, Michael arrives at Necessiter’s home, and as he waits to see the doctor, he thinks about Rebecca and sings her favorite song, then notices a female voice accompanying him. He follows the voice into the laboratory and realizes that it is emanating from the preserved brain of Anne Uumellmahaye. They are able to communicate telepathically, but only with each other. Necessiter enters and introduces Michael to a gorilla, claiming that the animal now possesses the mind of Beckerman. Michael returns to his hotel room and discovers Dolores on the window ledge, feigning a suicide attempt and claiming remorse for the pain she caused him. Michael rescues Dolores and they make love, after which he compliments her on her professional technique. Later, Anne’s telepathic cry for help brings Michael back to Necessiter’s home, where her brain is being readied for transfer to another gorilla. Michaels steals the brain and hides it in his hotel room. The next morning, Michael tells Dolores that he has decided to remain in Vienna for several months, and invites her to join him in his search for a rental home. Dolores declines, having already planned a tryst with a handsome waiter. After Michael and Dolores relocate to a cottage on the outskirts of the city, she notices her husband’s waning interest in the marriage, and later spies on him as he spends a romantic afternoon with the brain. Dolores confronts her husband, but is interrupted by another telephone call from Gladstone, who tells Michael of the inheritance, and mentions his previous conversation with Dolores. Realizing that Dolores is only interested in his money, Michael throws her into a mud puddle and promises to donate his inheritance to cranial research for the poor. When Michael tells Necessiter that he is in love with Anne, the doctor offers to transfer her mind into a new body, but they must act quickly because the brain has only a short time to live. While Michael’s search is underway, Dolores follows him with a loaded pistol and enters an elevator, where she is injected with window cleaner. Michael discovers her body, along with the murderer, celebrity Merv Griffin. He demands that Griffin surrender to the authorities, then races back to Necessiter’s laboratory with the corpse. Along the way, Michael is stopped by police for speeding, and has to undergo an elaborate series of tests to prove his sobriety. As he is about to drive away, the officers discover Dolores’ body, and pursue him to the laboratory. The transfer is completed as the police break down the door, but Michael is injured in the ensuing mayhem. He regains consciousness six weeks later in a Los Angeles hospital, and asks to see Anne, who now occupies Dolores’s reanimated body. Anne, a compulsive eater, apologizes for her noticeable weight gain, but Michael can find nothing wrong with her, although he encounters considerable difficulty while carrying her over the threshold of his home.