Tyrannical Nurse Ratched rules her ward in a mental hospital with a strict and unbending routine, unopposed by her patients, who remain cowed by mind-numbing medication and the threat of electric shock therapy. But her regime is disrupted by the arrival of McMurphy - the swaggering, fun-loving trickster with a devilish grin, who resolves to oppose her rules on behalf of his fellow inmates. His struggle is seen through the eyes of Chief Bromden, a seemingly mute patient who understands McMurphy's heroic attempt to battle with the powers that keep them imprisoned. A devastatingly honest portrayal of the boundaries between sanity and madness.