Dysfunctional, acid-tongued romance novelist Melvin Udall (Jack Nicholson), who suffers from an obsessive-compulsive disorder, takes pride in his ability to offend. At a nearby cafe, the only waitress willing to stand up to his sarcastic tirades is Carol Connelly (Helen Hunt), a single mother struggling to raise her chronically asthmatic son. In Melvin's West Village apartment building, talented contemporary artist Simon Nye (Greg Kinnear) lives across the hall from Melvin.