Melvin Udall, a cranky, bigoted, obsessive-compulsive writer of romantic fiction, is rude to everyone he meets, including his gay neighbor, Simon. After Simon is brutally attacked and hospitalized, Melvin finds his life turned upside down when he has to look after Simon's dog. In addition, Carol, the only waitress at the local diner who will tolerate him, leaves work to care for her chronically ill son, making it impossible for Melvin to eat breakfast.
Six-year-old Susan Walker has doubts about childhood's most enduring miracle—Santa Claus. Her mother told her the secret about Santa a long time ago, but, after meeting a special department store Santa who's convinced he's the real thing, Susan is given the most precious gift of all—something to believe in.