It is a fictional account of two actual Prohibition-era policemen, Izzy Einstein and Moe Smith, and their adventures in tracking down illegal bars and gangsters.

Former vaudeville entertainer Izzy Einstein (Jackie Gleason) volunteers; he is desperate to have a steady paycheck to support his wife, mother-in-law, and four daughters.

When the agent in charge of the local Prohibition Unit office asks Izzy why he wants to sign on for a dangerous job, especially at his age, Einstein makes a speech: "This is America.

Moe Smith (Art Carney), Izzy's old vaudeville partner, recently had his underground bar raided by the police and is spending too much time alone and drinking.

Izzy and Moe soon successfully raid underground bars all over the city, and arrest such high-profile people as the district attorney.

The agent's death affects Moe, who had considered quitting again to be with Dallas, but he decides to stay, giving his own version of the "This is America" speech to reporters.

Izzy and Moe then proceeded to rob the Dutch's big shipment of Bourbon that he was expecting, with help from Dallas, and also take the truck and its treasure to a police impound site.