Chicago, October 1932. The depths of the Great Depression, marked by unemployment and poverty. The only chance some people felt they had to rise out of poverty, if only for a short time, was to win the lottery or at the punch-boards. The mob saw this as an opportunity, by coming up with a numbers game. People picked a number from 0-999; their odds of winning were 1-in-a-1,00... the payoff was 600-to-1. The thousands of losers, pouring money into the mob, were never mentioned. Right now, mobster Phil Morrisey is pulling up in his fancy car, and making a big show for the crowd by giving today's winnings to a Mrs. Pollock...for her investment of 25 cents, she is now getting $150, a fortune by Depression standards. And all those watching are determined to bet again, convinced they will all be winners someday. Phil Morrisey has also attracted the attention of Eliot Ness and Agent Flaherty. Ness tells Phil that $400,000 out of every million collected goes to the Syndicat... for corruption, bribery, booze, prostitution. But Phil keeps working for his gangster father, Al Morrisey.
The Syndicate has all of Chicago divided into districts. There's trouble in Al Morrisey's district when one of his collectors, Larry Bayliss, welches on a bet; Wasson, the guy who was stiffed, knifes Larry and the killing makes headlines. A crooked police Captain comes into Ness' office to discuss the Bayliss killing. Ness tells the Captain, "Give me the name of every man on your force above the rank of sergeant who's on the take. Give me the name and address of the central bank of the numbers operation." The Captain leaves in a huff. Al Morrisey gets into more trouble; the crooked Captain and some of his cops arrest him. Then Pat Danning, the keyman in the operation, whose power is absolute, has to arrange to have a crooked lawyer spring him and crush the case. Ness and his men begin a series of raids, looking for the central office of the gambling racket. Danning has Al Morrisey dragged in for a "trial" by the Syndicate; Danning takes away half of his collectors because of the Bayliss killing, he also has his boys rough up Al Morrisey.
That night, Ness visits Al Morrisey at his home, to try to get information from him. But gangster Lippy is watching Morrisey, he spies through the window and sees him talking to Ness. When Pat Danning hears of this, he fingers Al Morrisey; he sends 2 of his hitmen, Frank and Benny, over to Al Morrisey the next morning, they give him 3 slugs in the pump. With his father dead, Phil Morrisey sings to Ness. Phil tells Ness that the central operation is at the Golden Farms Milk Company (and just in time, that night Danning was going to move his operation to the South Shores Transit Corporation); Phil also tells him that Sampson is the bookkeeper. That night, Ness and his men raid the place, there's a big shootout. All but 5 of the crooks get shot; 4 are arrested and they let Sampson escape with the books. Ness follows Sampson, who leads him right to Pat Danning...who is playing poker with 7 crooks, one of them the crooked police Captain. Ness has smashed another of the mob's operations.