One man’s struggle to fight the system becomes a journey for everyone. It all starts out with McMurphy, a man sent to a work farm for statutory rape. It seems that he gets sent to a mental hospital for an evaluation. The reality is that he just fine just rebellious. As he struggles with his own personal demons, and fights the very system that is supposed to be helping them all, this story turns in to a roller coaster ride for all of them.
McMurphy's ward is run by Nurse Mildred Ratched, using humiliation, unpleasant medical treatments and a boring daily routine to control the patients. McMurphy finds the other patients are more afraid of Ratched than the outside world. McMurphy quickly puts himself in the leader position. When McMurphy's card games win away everyone's cigarettes, Ratched takes the cigarettes and rations them out. McMurphy calls for votes to challenge her and gets nowhere. McMurphy steals a hospital bus, with the other patients on it, stops to pick up Candy and takes the group deep sea fishing.
Soon after, however, McMurphy learns that Ratched and the doctors have the power to keep him committed as long as they want. During one of her group sessions, Cheswick's gets upset and him, McMurphy and the Chief, believed to be deaf and mute, get into a fight with the orderlies. They are sent for electroconvulsive therapy. While McMurphy and the Chief wait their turn, McMurphy offers Chief a piece of gum, and Chief murmurs "Thank you". McMurphy is thrilled to find Chief is neither deaf nor mute, and is just playing the part. After the electroshock therapy, McMurphy heads back onto the ward faking illness, before he loudly greets his fellow patients, letting everyone know that it only charged him up that much more.
But the struggle with Ratched is taking its toll, and without a for sure release date, McMurphy plans an escape. He phones Candy to bring her friend Rose and some alcohol to the hospital late one night. McMurphy pays off the night orderly to...