A club of boys gets a mayor elected during boys week in order to free their new member, who has been framed for arson by corrupt men.
At the state reformatory Gabe Ryan (Frankie Thomas) is paroled to his sister Joy Ryan (Ann Sheridan). In their new neighborhood Gabe fights Leo Finnegan (Leo Gorcey), wins, and is initiated with tests into the Termite club. They put out a fire in a basement. Owner Kroner (Bernard Nedell) lets them go, but his boss Martino (Eduardo Ciannelli) tells him to cast suspicion on Gabe. Deputy D. A. Pat Remson (Ronald Reagan) questions Gabe and gets coffee from Joy. Kroner tells kids to leave his lot, and Sleepy Arkelian (Bernard Punsly) is hurt in the street. Joy knows it is corrupt politics and appeals to Martino and his civic league. Martino tells Haines (Cy Kendall) and Kroner to burn a building and blame Gabe by getting him to hate Kroner. Peggy Finnegan (Bonita Granville) urges Gabe to run for boys mayor. Pat kisses Joy. Sleepy is trapped in a burning building and is killed. Pat blames fire commissioner Haines. Sleepy's mother (Marjorie Main) is devastated, and Pat has Gabe arrested.
Witnesses including Miss Hannaberry (Margaret Hamilton) and Haines testify against Gabe, who says they are lying. District Attorney Remson (Henry O'Neill) persuades the jury, and Gabe is sentenced to ten years. Termite leader Billy Shafter (Billy Halop) runs for mayor. Termites discourage other candidates with rough tactics as Billy studies. Mayor Dooley (Berton Churchill) announces that Billy won the contest to be mayor for one week. Billy appoints as officers Termites Leo, Huntz, Luigi (Gabriel Dell), and Bernie Smith (Bobby Jordan) along with Peggy for street cleaning. Pat proposes to Joy that they marry, but she declines. Mayor Dooley leaves Gildersleeve (Grady Sutton) to watch Billy, who has his cabinet lock up Gildersleeve. They go to get Gabe from jail but have to go to a judge, who has them thrown out. They attack Gildersleeve, and the police chief calls Pat, who says they must find those who framed Gabe. Termites go after the records of Haines. Bernie's father hints of an impending fire for insurance. Pat takes Haines' account book to his father, the D. A. Then Pat, an attorney (Minor Watson), and the Termites find evidence along with Kroner and Shuffle (Dick Rich), who are arrested; but their lawyer gets them released.
Peggy says that Shuffle can be arrested for spitting on the sidewalk. The attorney and Leo have Kroner and Shuffle arrested and put in stocks. Billy accuses them of killing Sleepy. News reports Boys Week terror, and Mayor Dooley heads back. The lawyer can't free them and goes to Martino, who flees. Pat gets Kroner to talk. When Dooley arrives, Termites grab Haines. Pat shows Dooley Kroner's confession and congratulates him. In the final scene the city is cleaned up and has playgrounds as Pat invites kids to his wedding.
The young spirit of this drama has juveniles reforming corruption by democratic and legal methods with occasional strong-arm tactics.