May 17, 1932. There are many free soup kitchens in Chicago, but one of them in the skid row section is really a front; upstairs, gangster Chez Goshen, twice convicted of white slavery, has his office. His partners in crime are the powerful, nationwide vice ring known as The Group, represented by hood Vic Cassandros. Chez's niece is Ginnie Littlesmith, who runs the soup kitchen, and she is not involved in the rackets. Downstairs, Enrico Rossi is working undercover--he's dressed in dirty old clothes, and phones Ness; Eliot tells him the raid is set for 12:45.
But Vic is soon tipped of Ness' impending raid; Vic goes upstairs and demands the ledger books from Goshen. But Goshen only wants to escape via the trapdoor, and tells Vic he'll never get the books. Vic shoots him, leaving him fatally wounded; but the tough old guy doesn't die right away--before he croaks he turns the ledgers over to his niece, Ginnie Littlesmith, and tells her they'd be worth $100,000 to the Group.
Anxious to get their business ledgers back are the heads of the Group: Ben Poe (owner of string of laundries and restaurants, but making most of his money from white slavery), "Little" Augie Tolan (narcotics czar of the Southern states), Smitty Kopek (head of the European drug combine), and Maria LaRose (daughter of a gangland chief). Ginnie meets with them, and asks for $100,000 for the ledgers. They make a counteroffer: $500 for the ledgers, and she gets to live.
Ginnie goes back to her hotel room; Vic Cassandros and Owen had orders to follow her. Owen roughs her up, but Vic goes soft on her; he tells Owen to leave. Ginnie seems like a nice girl; but Vic grabs her and says, "You're a little dirty, Ginnie, just like I'm a little clean." He wants her to get the 100,000 bucks--and then split it with him. Vic wants to run away with her and go to Mexico; Ginnie doesn't know he's the one that shot her uncle. Ness and Lee Hobson just miss Ginnie as she takes a train home, for her sister's wedding. Ness interrogates Vic, but gets no information.
The first week of May 1932, gang war erupts on the Northside; the Group smashes all competing mobs, to become as powerful as the forerunner, the Bugs Moran gang. Ness tracks Ginnie down in her hometown, where she went for Laura's wedding. Ginnie hightails it back to Chicago, and Vic is waiting for her, with the offer of running off to Mexico again. Ginnie doesn't trust him--she thinks as soon as she gets the money, Vic will kill her. Minutes later Ness knocks at her door, Vic hides in another room; Ginnie tells Ness nothing.
Back at the Group's hideout, Vic tells Maria LaRose he will use a silencer on Ginnie. That night, Ginnie goes to a Chinese laundry that's a front for the Group; Rossi tails her. Ginnie meets with all the bosses and says she had the ledgers photographed; the negatives are in an envelope addressed to Eliot Ness, to be mailed in the event of her death. Just then Ness and his men drive up. The gangsters douse the ledgers with gasoline and set them on fire. Outside, a hitman blasts at the Untouchables with a chopper; Ness shoots him. Inside, Lee Hobson shoots Augie Tolan; Ness puts a towel over the burning books.
Back at Ginnie's hotel room, Vic is waiting for her; the story about having the books photographed was his idea. Vic opens Ginnie's case and sees the $100,000. He said he had orders to kill her, put produces 2 tickets to Mexico instead. Just then, Maria LaRose and a hitman show up; the hit-man shoots Vic. Then Ness and Enrico Rossi and Lee Hobson show up. The half-burned books still provided enough evidence to result in stiff prison terms for the leaders of the Group; this marked the end of their crime syndicate. As for Ginnie, she got a suspended sentence for withholding evidence, and led a suspended life thereafter as a model spinster.