Chief Bromden serves as the narrator for One Flew Over the Cuckoo’s Nest. He has been a patient at the unnamed Oregon psych ward for ten years, and suffers from debilitating hallucinations of fog. While Chief Bromden is aware of his surroundings, he has pretended to be both deaf and dumb for the duration of his commitment. On the ward, all of the patients are men divided into Acutes (curable) and Chronics (vegetables). Nurse Ratched rules over the ward with an iron fist. If anyone dares to go against her, they are punished with shock treatment, or in severe cases, a lobotomy.
Randle McMurphy is the protagonist of the novel, and his arrival after a transfer from a Pendleton Work Farm marks the beginning of an unprecedented liberation in the ward. McMurphy introduces himself to both the Acutes and Chronics as a gambler and womanizer. After the first group therapy session, he claims that Ratched is a ball-breaker. McMurphy bets the other patients that he can cause Ratched to lose her temper in his first week, and wins. After a group therapy session where Ratched refuses to let the men watch the World Series, which comes on during Ratched’s scheduling cleaning of the ward, McMurphy protests by refusing to do his chores and sitting in front of the blank television. The other men join. Ratched is incensed and demands that they get back to work, but the men refuse.
McMurphy is thrilled with his victory. The patients on the ward expect for Ratched to retaliate by sending McMurphy to shock treatment, but she fears that sending McMurphy away will turn him into a martyr, and that after enough time has passed the other men will see that McMurphy is actually egotistical coward.
McMurphy soon learns that being involuntarily committed (which he is) leaves you at the mercy of the hospital staff to determine your freedom. He had previously thought that he would get to leave when his term was up. He begins to abide by the strict rules, not wanting to jeopardize his chance at getting out. It is too late, though, because the other patients already see McMurphy as their leader against Ratched. As the patients begin to realize McMurphy has submitted to her authority, Charles Cheswick becomes upset and drowns in the pool, which the doctor rules a possible suicide. McMurphy is torn up by Cheswick’s death, and realize how the other men see him. He playacts for a little longer at being obedient, then punches through the nurse station window as Ratched sits inside after she takes away game room privileges as a punitive measure for the men’s World Series protest.
McMurphy sets up a fishing trip for ten patients and himself. On the boat, he is largely absent below deck—allowing the men to take charge of steering and catching large fish, enabling them to feel free, in control, and masculine. McMurphy also devises a scheme for Billy Bibbit to lose his virginity to a prostitute named Candy Starr by sneaking her into the ward. The men return from the trip feeling empowered.
McMurphy and Chief Bromden get in a fight with some of the aides after they taunt George Sorenson in the shower after their fishing expedition. Both McMurphy and Chief Bromden are sent to Disturbed for shock treatment. Ratched brings him back to the ward to dispel the myth that McMurphy is immune to the treatments. McMurphy is encouraged by the men to escape, but he uses Bibbit’s scheduled date that evening as an excuse not to leave. After bribing the night aide, Mr. Turkle, the men sneak Candy into the ward and a large party takes place with drinking, smoking, and Bibbit losing his virginity. Dale Harding urges McMurphy to escape to Mexico. McMurphy promises to, but falls asleep instead.
The aides discover all the men in the morning. Nurse Ratched finds Bibbit with Candy and threatens to tell his mother. He is so distraught that he slits his throat, killing himself. McMurphy, blaming Ratched for Bibbit’s death, attacks her, ripping her uniform. She sends McMurphy to be lobotomized and he’s returned to the ward as a Chronic. However, her power is broken. Most of the men check out of the hospital or transfer to different wards. Chief Bromden suffocates McMurphy with a pillow as an act of mercy, then throws the impossibly heavy control panel out of a window and escapes the hospital.