Gil Renard, a knife salesman, is a baseball fanatic in the strongest sense of the word. His BMW 325i sports the vanity plate WNSOX, and he risks his job and his relationship with his son to attend the first home game of the season. He is convinced that free agent Bobby Rayburn, signed to the White Sox with a lucrative multiyear contract, will take the Sox to the World Series championship.
Renard’s life soon falls apart. When he abandons his son at the opening day game, his former wife obtains a restraining order against him seeing his son, and his failure to meet quotas costs him his job at the company his father founded. Possibly nearly as bad for him, Rayburn falls into a slump and the White Sox show dim prospects for the season. He overhears a fight between Rayburn and another player, who insists on keeping the jersey number Rayburn used on his former team. Renard becomes convinced that he can help Rayburn out of his slump by getting his jersey number for him.
All Renard seems to have left in his own life are his memories of his own glorious past as a baseball pitcher. He visits his former catcher, who has become a thief, and assists him in a robbery, paradoxically stealing knives made by his father that he had sold to a collector. The robbery begins a series of criminal events that are part of Renard’s quest to help Rayburn. Renard’s actions increasingly show signs of his mental instability, and by the book’s climax he has clearly crossed the border from fandom to insanity.