The fourth and final section of this novel depicts the final showdown between Randle Patrick McMurphy and Nurse Ratched. This part begins with Chief telling the reader that Ratched began planning a counterattack on McMurphy while he and the group were on their fishing excursion. Chief somewhat omnisciently relates that Ratched knows that people eventually grow suspicious of individuals who seemingly operate selflessly on behalf of others.
She plants the seeds of dissent in the group while McMurphy takes a phone call. She prompts the group to question McMurphy's motive when she tells them he has won more than $300 from the other patients. While the patients enjoy the additional benefits that McMurphy has provided, they suspect that he may be motivated by more than philanthropic impulses.
Ratched manipulates the conversation by asking if any member of the group considers McMurphy a "martyr or a saint." She continues that McMurphy is taking credit for giving the patients items and freedoms that were not his to give. She climaxes her attack on McMurphy by revealing to the patients that McMurphy made money off the patients when he arranged the fishing trip. Ratched tells Billy Bibbit, McMurphy's most staunch defender, that she doesn't disapprove of McMurphy's actions, but that she feels the patients shouldn't delude themselves that McMurphy's actions are selfless.
After the meeting, Harding explains to the group that McMurphy is an example of American entrepreneurialism and would be embarrassed if he thought others claimed his motives were pure. He calls McMurphy "a sharp operator, level-headed as they come," and adds that "everything he's done was done with reason."
Bibbit disagrees with Harding, telling him that McMurphy couldn't possibly harbor ulterior motives in teaching Bibbit how to dance. Chief says that he and Bibbit are the only patients who believe in McMurphy. McMurphy then appears and asks Bibbit to send money to Candy Starr so that she can visit. When Bibbit says that the ten dollars McMurphy tells him to send Starr is more than bus fare usually costs, McMurphy admits that he has asked Starr to bring alcohol when she visits.
In private, McMurphy asks Chief to lift the control panel. When Chief shows him that he can perform the task, McMurphy baits the group into a bet that pays five to one that no one can lift the panel. Learning that Ratched has ordered delousing showers for all the patients returned from the fishing trip, Chief says he wishes he could take the shower instead of lifting the panel. He feels that he's helping McMurphy cheat his friends out of their money. He performs the feat anyway and leaves the room in disgust.
McMurphy follows Chief to give him five dollars. He asks Chief why all the patients are treating him suspiciously. Chief responds that it's because McMurphy always appears to be winning things. McMurphy responds wearily, "Winning, for Christsakes
. Hoo boy, winning."
The group is led to the showers for delousing. The members taunt the African-American aides by making wisecracks and breaking wind. All is jovial until the aide Washington begins to harass Rub-a-Dub George, who is obsessed with cleanliness but never uses soap. As George becomes more upset at Washington's claims that he is infested with bugs, McMurphy steps in to defend George. Calling Washington several negative sexual and racial epithets, McMurphy shoves Washington away from George. Washington, still angry with McMurphy for bloodying his nose in the basketball game, strikes him.
Noting that McMurphy's voice reveals a "helpless, cornered despair," Chief relates the details of the ensuing fight. The aides outnumber McMurphy until Chief assists him. After they win the fight, McMurphy and Chief are handcuffed and led to the Disturbed Ward.
McMurphy's motives are questioned by the group, prompted by the ideas planted by Nurse Ratched. Their suspicions are confirmed, however, when McMurphy asks Bibbit for extra money to pay for Starr's visit, and he tricks the patients into betting that Chief can't lift the control panel. The patients' perception that McMurphy is always "winning" eventually leads to McMurphy's downfall.
McMurphy's response to Chief's comment that he's always winning indicates that his rebellious behavior is taking its toll on McMurphy, which is underscored by his defending George from Washington in the showers.
McMurphy physically defends George, knowing that the other aides will come to Washington's assistance. Describing the "helpless, cornered despair in McMurphy's voice," Chief indicates that McMurphy is trapped into defending George and has no choice.
vermin various insects, bugs, or small animals regarded as pests because they are destructive, disesase-carrying, and so on, as flies, lice, rats, or weasels.