A rookie pitcher helps the St. Louis Cardinals win the pennant even though someone murders three players in this adaptation of a novel by Cortland Fitzsimmons.
Rookie pitcher Larry Kelly (Robert Young) is immediately attracted to club secretary Frances Clark (Madge Evans). Manager Pop Clark (David Landau) tells ex-players involved with gamblers to stay away, because baseball is a clean game. Clark tells his daughter he went into debt to buy Kelly and may lose the team if they don't win. Comic relief is provided by running arguments between catcher "Truck" Hogan (Nat Pendleton) and umpire "Crawfish" O'Toole (Ted Healy) about the latter's eyesight. The reporter Jimmie Downey (Paul Kelly) asks the gambler Joe Karns (C. Henry Gordon) why he is there. Kelly turns down an invitation from Karns, and the team's baseball gloves are found drugged. Frances stops Kelly and Frank Higgins (Robert Livingston) from fighting, and their pitching puts St. Louis in second place. Karns is worried because the odds on St. Louis were 20-1.
Kelly finds $10,000 with a note to lose the game, but he is persuaded to take the money to manager Clark. Jimmie writes the story, and Kelly proves he is honest by pitching a no-hitter. However, a tire is shot, and he is injured in the car crash. Dunk Spencer is shot and killed in a game. A rifle is found. Jimmie asks Karns which player is next, and he promises to watch the gambler. Hogan calls Higgins to the phone, and Higgins is found dead, strangled. Hogan wins the game, and O'Toole buys him a hot-dog; but someone replaces the mustard, and Hogan is poisoned. Before he can say who called Higgins to the phone, Hogan dies.
Clark opposes canceling the last game. Frances asks him not to pitch Kelly; but Jimmie argues they must pitch Kelly so they can catch the murderer. Frances tells Kelly not to play; realizing she loves him, he kisses her. At the ballpark the fans are being searched. A hand puts something in Kelly's coat, and Kelly throws the ball at him. A watch is found and explodes. Patterson, an ex-player and groundskeeper, pulls a gun and is caught. He explains he wanted to be manager after Clark went broke. St. Louis wins the game and the pennant, and Frances and Kelly embrace happily.
The year this film was made the wacky "gas-house gang" of St. Louis Cardinals had one of baseball's best teams ever with Dizzy Dean. This story plays out a murder mystery in the popular sport. Although baseball's record was marred once by the 1919 Black Sox gambling scandal, fortunately the game has been free of this kind of violence.