At the State Correctional Mental Facility in Cicero County, Illinois, Psychiatric Director Dr. Lawrence Baird tells inmate John Burns that he does not believe John is mentally ill, and threatens to transfer him back to prison if John crosses him again. In Los Angeles, California, Dr. George Maitlin, a psychiatrist and host of the popular radio program “Mind Your Mind,” recovers from a nervous breakdown. Maitlin tells his lawyer, Harvey Michaels, to find a psychiatrist to temporarily take over his practice and radio show while he recuperates in London, England, with his wife, Vera. Michaels’s assistant, Perry Kovin, has found Dr. Lawrence Baird to be Maitlin’s replacement. Meanwhile after causing a commotion, John Burns is placed in a straitjacket and sent to Dr. Baird’s office. Baird informs John he is being sent to Statesville Sanitarium the following day. After Baird is paged away, the telephone rings, and John Burns answers. Michaels offers the doctor the job to take over Maitlin’s practice and radio program during his recuperation. Pretending to be Baird, John agrees. John escapes with assistance of Robin, Dr. Baird’s secretary. At the airport, John steals an overcoat and a scarf to cover up his prison jumpsuit and picks up the ticket left waiting for Dr. Baird. Upon arriving at the Los Angeles airport, John is met by Maitlin’s associate, Dr. Laura Rollins, and Hendricks, radio station manager and producer of “Mind Over Mind.” Just then, Donald Becker, a former priest wearing a cardboard sign reading “People For The Ethical Treatment of Plants” approaches and recognizes John’s prison-issued pants. However, Hendricks has a nearby police officer arrest Donald Becker. In London, Maitlin tells Vera that his nervous breakdown was caused by guilt over having an affair with a patient. Afterward, Maitlin receives a telephone call from Harvey Michaels passing on John Burns’s request for $200,000. Maitlin reluctantly agrees. Meanwhile, John hosts Maitlin’s radio program and becomes a huge success, impressing listeners with his candor and obscene language. Before the end of the program, he invites callers to visit him the next day at Maitlin’s office in Beverly Hills, California, for free therapy. As he leaves the station, John is informed that Donald Becker called from the Los Angeles Psychiatric Hospital to speak to him. John goes to the hospital and signs Becker’s release forms. Afterward, John lets Becker stay with him at his hotel. The following day, they arrive at Maitlin’s office and see a crowd of people waiting. Dividing patients by their ailments, John Burns rents buses and takes them to a baseball game. Later, Harvey Michaels lets John know that he is more popular than Maitlin, and wants him to accept an award on Maitlin’s behalf from the Greater Los Angeles Neuropsychiatric Society (GLANS). Donald Becker tells John that although he has not trusted anyone in a long time, he trusts John. Later, Becker finds an airline ticket to Mexico City, Mexico, that John planned to use once he received his $200,000 cash payment. Disgusted by John’s deception, Becker leaves. In London, Vera confesses to Maitlin that she has been having an affair for a year and a half with his friend, but Maitlin believes she is lying to get back at him for his own affair. Later, Maitlin attends a lunch at the International Psychiatric Convention and meets the real Dr. Lawrence Baird. Confused, the men call Maitlin’s office and learn that John Burns has been passing himself off as Baird. Maitlin tells Vera he is going to kill Harvey Michaels, but Vera thinks he is referring to her affair with Michaels instead of his mistake in hiring John Burns, and confesses. Confused, Dr. Baird and Maitlin to fly to Los Angeles. At his office, Maitlin finds his handgun, planning to get revenge on John Burns and Michaels, but Baird insists they call the police. To stop Baird from phoning, Maitlin knocks him unconscious. That evening, John Burns goes to pick up Dr. Laura Rollins for the award ceremony. However, Laura tells him she is not going, as she learned he is a fraud. At the ceremony, Harvey Michaels gives John the promised $200,000 in a briefcase. As John accepts the evening’s award, Maitlin arrives demanding his $200,000. John escapes to the airport. Meanwhile, Dr. Baird regains consciousness and goes to the award ceremony. However, without identification, no one believes him to be the real Dr. Lawrence Baird, and he is arrested. While John waits for his departure, television news reports that Donald Becker is threatening to jump off the standing on the “Y” of the Hollywood sign. Feeling guilty, John stores the briefcase in an airport locker and heads to the Hollywood sign, followed by Maitlin and Michaels. John confesses to Becker that he did escape from a mental facility for prisoners, and gives Becker the locker key, telling him the money is now his. Afterward, they are both arrested, but John convinces police to release Becker. While John is driven to jail, Maitlin, upset over his missing money, fires his gun at Michaels. When he misses, the police arrest Maitlin as television news cameras record the incident. Maitlin is sent to the Los Angeles Psychiatric Hospital as a patient, along with Dr. Baird. Later, John is being transported to Lompoc prison in a police van. Along the way, the van stops at the sight of an accident. When the guards go to investigate, Donald Becker and Dr. Laura Rollins steal the van, rescuing John. However, a guard shoots the van motor. Pulling over, Laura wishes them good luck and catches a bus home. Becker and John hop on a motorcycle Becker purchased with part of John’s $200,000 and escape together.