Simon Birch is a movie that is very loosely based off of John Irving's A Prayer for Owen Meany. It opens with the adult Joe Wentworth (Jim Carey) at the grave of his childhood best friend, Simon Birch, whose headstone shows he died at 12. Joe explains that Simon is the reason he believes in God. The film then flashes back to Joe's childhood, where he and Simon attend Sunday school together. Simon has a condition that makes him physically smaller than other kids his age, and his voice is "funny." This most often results in the other kids treating him like he is a toy.
Even as a bit of an outcast, Simon Birch has a very strong sense of faith, and believes that God has a purpose for his life and his size. Simon is also mostly neglected at home. As a result, he spends most of his time at Joe's house. Joe is the only child of his very young and uniquely beautiful mother, Rebecca. His father's identity is unknown. Most of the boys and men in town are in love with Rebecca, Simon Birch included. When she brings home a new boyfriend for dinner one night, Joe decides it is time to learn his father's identity.
Then, one day, Simon Birch hits a foul ball at a little league game, which strikes Rebecca on the temple and kills her. The rest of the film reveals the growth of the boys' friendhip, despite this tragedy, as well as a growth in the themes of faith, purpose, and fate. Included is a swimming scene in which Simon Birch has Joe time how long he can hold his breath. Later, there is a bus accident in a body of water, and Simon Birch uses this gift, and his size, to save many of the children on board.
In the end, Simon Birch dies, but gives Joe the clues and tools to discovering his father's identity. Though the premise of the film is depressing, there are enough moments of comic relief that it has been classified by some as a comedy.