An obsessive-compulsive writer comes out of his shell to help a struggling waitress and an injured artist.

Melvin Udall is a sarcastic writer who lives alone in an apartment, eats at the same restaurant each day, is afraid of germs, and generally hates people. His neighbor, Simon, is a gay artist whose dog is constantly becoming entangled in Melvin's life annoying Melvin and giving rise to much anti-homosexual sentiment on his part. Carol is a waitress at Melvin's usual eating spot who is trying to take care of an asthmatic son and has to suffer Melvins obnoxious behavior. However, the door to Melvin's self-awakening is opened by Simon's dog who Melvin has to watch after Simon is brutally mugged. He comes to love the dog and respect Simon, and to see that Carol's son receives much-needed medical care.