In a tense, psychological thriller, Dale Nelson, a mentally ill gardener, decapitates his wealthy boss, Mrs. Townsend, with a pair of shears. He then surrenders to the police, is deemed insane, and sent to a mental institution ruled by psychiatrist Dr. Edwina Beighley. During Nelson’s hearing, Beighley learns that Martin Ashley may have buried a substantial sum—$1 million—belonging to the late Mrs. Townsend.
Townsend’s executor, Harley Manning, grows suspicious and hires Nelson to simulate madness and infiltrate the same facility. The plan is straightforward: Nelson must locate the missing money and secure a $10,000 payment that Manning has placed in a safety deposit box in Nelson’s name, with the key withheld until the job is done. To convincingly pretend to be insane, Nelson studies psychology and gardening, and he even creates a dramatic entrance by breaking a storefront window and shouting against “conformity,” signaling his willingness to go to extremes.
Inside the hospital, Nelson is assigned to gardening as part of occupational therapy, where he first clashes with Ashley but soon wins him over through his botanical knowledge and admiration for a special rose that Ashley developed. Nelson’s charisma and expertise impress Ashley and help him earn a place in a competition tied to his former employer, showcasing Nelson’s potential value beyond his presumed insanity. He also forms an unusual bond with Cynthia Lee Albright, a patient who has deep-seated issues with men but gradually begins to trust Nelson’s steady, understanding presence.
Beighley, hungry for funds to support her research into catatonia, uses hypnosis on Ashley to probe for the location of the money. When she realizes Nelson is an imposter, she subjects him to electroconvulsive therapy as a form of torture. After regaining consciousness, Nelson is questioned about his motives, and Beighley threatens to expose him for illegally entering the institution. He warns her that he could reveal her illegal use of shock treatment on a sane person. In response, she administers a second staggeringly powerful dose, and Nelson is left in a precarious state of catatonia, with a third injection threatening permanent impairment.
To avoid a third injection, Nelson must continue to feign catatonia, now confined to a wheelchair. A visit from Cynthia gives him hope, and she signals to him when the attendant approaches. That evening, during a hospital dance, Ashley wheels a supposedly “catatonic” Nelson outside and scolds him for betraying Beighley’s trust. Cynthia slips him a stolen key as the attendant nears, and Nelson escapes when an orderly escorts him back to his room.
Fleeing to Manning’s residence, Nelson discovers that Manning has died of a heart attack, and Manning’s secretary cannot confirm the impersonation. The secretary calls the police, but Nelson overhears the exchange and slips away before they arrive.
Nelson finally makes it to the Townsend estate, where Ashley and Beighley are digging a fresh hole for the money. The sack that Ashley uncovers contains only the ashes of burnt money, not the fortune they crave. Beighley’s fevered determination to recover the funds drives her into a frenzy, and Ashley is fatally impaled on a spiked fence during their struggle. Beighley descends into madness, convinced the money must be buried somewhere on the property.
In the end, Nelson testifies at Beighley’s sanity hearing, and she is institutionalized, stubbornly insisting that the money exists “after 31 separate hours” of questioning Ashley. With Beighley debriefed and the truth laid bare, Cynthia is discharged, and Nelson leaves the institution alongside her, stepping back into the outside world with a new sense of possibility.
