The 1919 Chicago White Sox are considered the greatest team in baseball and, in fact, one of the greatest ever assembled to that point. However, the team's owner, Charles Comiskey, is a skinflint with little inclination to reward his players for a spectacular season.
When gamblers "Sleepy" Bill Burns and Billy Maharg gets wind of the players' discontent, they offer a select group of Sox — including star Knuckleball pitcher Eddie Cicotte — more money to play badly than they would have earned by winning the World Series against the Cincinnati Reds.
A number of players, including Chick Gandil, Swede Risberg, and Lefty Williams, go along with the scheme. The team's greatest star, Shoeless Joe Jackson, is depicted as being not very bright and not entirely sure what is going on. Buck Weaver, meanwhile, is included with the seven others but insists that he wants nothing to do with the fix.
When the best-of-nine series begins, Cicotte, who led the majors with a 29—7 record and had an era of just 1.82 for the year, deliberately hits Reds leadoff hitter Morrie Rath in the back with his second pitch in a prearranged signal to gangster Arnold Rothstein that the fix was on (Rothstein allegedly financed the fix). Cicotte then pitches poorly and gave up 5 runs in four innings, four of them in the 4th which included giving up a triple to Reds pitcher Walter "Dutch" Ruether. He is then relieved by team manager Kid Gleason, though the Sox lose the first game 9–1. It was earlier revealed that Cicotte's motivation for going along with the Fix was that Comiskey had refused him a promised $10,000 bonus should he win 30 games for the year. Cicotte had been on track for the 30 wins before intervention by Comiskey late in the season had seen Gleason bench him for 2 weeks (missing 5 starts) which caused him to miss out on his 30 win bonus. With the pennant winners at the time automatically qualifying for the World Series, Comiskey's reason for having Cicotte benched was to save the veteran 35 year old's arm for the series.
Williams also pitched poorly in Game 2, while Gandil, Risberg and Hap Felsch made glaring mistakes on the field. Several of the players become upset however, when the various gamblers involved fail to pay their promised money up front.
Chicago journalists Ring Lardner and Hugh Fullerton grow increasingly suspicious. Meanwhile Kid Gleason continues to hear rumors of a fix, but he remains confident that his boys will come through in the end.
A third pitcher not in on the scam, Dickey Kerr, wins Game 3 for the Sox, making both gamblers and teammates uncomfortable. Other teammates such as catcher Ray Schalk continue to play hard, while Weaver and Jackson show no visible signs of taking a dive with Weaver continuing to deny being in on the fix. Cicotte loses again in Game 4. With the championship now in jeopardy, Gleason intends to bench him from his next start, but Cicotte begs for another chance. The manager reluctantly agrees and is rewarded with an easy Game 7 win. Unpaid by the gamblers, Williams also intends to do his best, but when his wife's life is threatened, he purposely pitches badly to lose the final game.
Cincinnati wins the World Series (5 games to 3) to the shock of Sox fans. Even worse, sportswriter Fullerton exposes the strong possibility that this series was not on the level. His findings cause Comiskey and the other owners to appoint a new commissioner of baseball, Kenesaw Mountain Landis, and give him complete authority over the sport.
Eight players are indicted and brought to trial. Cicotte, Williams, and Jackson even sign confessions. But in court, while Weaver maintains his innocence, the confessions are mysteriously found to be stolen, and the popular Chicago players are found not guilty. While they celebrate, however, Judge Landis bans all eight from professional baseball for life, citing their failure to reveal being approached by gambling interests in the first place.
Weaver is among those exiled from the game. The final scene shows him in the bleachers of a New Jersey minor league ballpark in 1925, watching Jackson play under an assumed name.