Due to a shortage of police officers, the newly-elected mayor of an unnamed American city requires the police department to accept all willing recruits. Carey Mahoney is an easy-going man who has repeatedly gotten in legal trouble when standing up to arrogant people. Captain Reed has been lenient because he knew Mahoney's father, a policeman. To avoid jail, Mahoney reluctantly joins the police force, planning to be thrown out as a loophole. The chief of police, Henry Hurst, outraged by the Mayor's plan, wants the new cadets to be forced to quit rather than being thrown out.