Headstrong yet aimless, Will Hunting has a genius-level IQ but chooses to work as a janitor at MIT. When he secretly solves highly difficult graduate-level math problems, his talents are discovered by Professor Gerald Lambeau, who decides to help the misguided youth reach his potential. When Will is arrested for attacking a police officer, Professor Lambeau makes a deal to get leniency for him if he gets court-ordered therapy. Eventually, therapist Dr. Sean Maguire helps Will confront the demons that are holding him back.

When Dr. Anthony Edwardes arrives at a Vermont mental hospital to replace the outgoing hospital director, Dr. Constance Peterson, a psychoanalyst, discovers Edwardes is actually an impostor. The man confesses that the real Dr. Edwardes is dead and fears he may have killed him, but cannot recall anything. Dr. Peterson, however is convinced his impostor is innocent of the man's murder, and joins him on a quest to unravel his amnesia through psychoanalysis.