A Beautiful Mind is a film which tells us the story about John Nash, a new graduate student at Princeton University and a recipient of the prestigious Carnegie Prize for mathematics. During his stay at the university, unknowingly, he started to develop paranoid schizophrenia wherein he hallucinates about certain events and people like his roommate, Charles Herman, a literature student who shares a room with him although he is promised to have a single person room and eventually became his bestfriend; Marcee, Charles' niece; and William Parcher, a person who belongs to the United States Department of Defense and gives him a new assignment, that is, to look for patterns in magazines and newspapers to thwart a Soviet plot.
After sometime and during his stay on teaching, he had met Alicia Larde and eventually, the two fell inlove and married. The first few months, their relationship had been okay. But after being chased by some Russian agents, John became more paranoid and begins to behave erratically. Alicia, observing his behavior, then informs a psychiatric hospital and there he even thinks that the officials of the psychiatric facility as Soviet kidnappers. Desperate to help her husband, Alicia asked John's friends and retrieves his “top secret” documes and told John that it was all in his mind and is not real.
John was given medications but being frustrated by its negative side-effects, he stops taking it which triggers his psychosis. He almost drowned his son and even hurts Alicia due to his hallucinations, but was then able to realize it was just his imagination because when he had seen Marcee, he realized that she doesn't aged. Only then does he accept that although all these three people seem completely real, they are in fact part of his hallucinations. Due to this, John and Alicia decided to try to live with his abnormal condition and try to ignore all of them. In the end, John eventually earns the privilege...