Chicago. November 9, 1932. Al Capone was in prison, and Frank Nitti was running his Organization. But other crime overlords were ready to take over, the biggest being Joe Kulak, from St. Louis. Joe Kulak was called "The Teacher" because he had trained so many Underworld big-shots, and given them their start. Eliot Ness and his men keep tabs on Kulak from the moment he arrives in the Windy City. Kulak goes to the Westside Athletic Club, a front for crime boss Arnie Seeger.
In his office, Seegar talks to Kulak and lays out his plans for the whole country: gambling, whiskey, houses (of prostitution), dope. Seegar figures to assign territories:Bouchard in New Orleans, Nicholson in K.C., Danny Kurtz (his lieutenant, sitting right next to him) for Pittsburgh...Kulak interrupts him, saying he already has Malone for Pittsburgh. Kurtz loses his temper over being cut out; (so Seeger decides to have Kurtz rubbed out that night). Seegar desperately wants Kulak to attend his upcoming meeting, with six crime overlords from all over the country; without Kulak, they won't go along with Seegar's nationwide plan. Kulak just tells Seegar he'll "think it over."
Later Maxie Schram, a small-time schlep who just got out after serving 3 years in Joliet, phones the Athletic Club, wanting to talk to his old boss Seegar. Kurtz tells him to drop by around 10:30 p.m. Schram goes inside, the club is closed and dark; he sees somebody (Seegar's boy Dutch) stab Kurtz, and Schram takes off running. Rico had been staking out the Athletic Club; Ness and his men pick up Schram, at the 15-cents a night flophouse where he's sleeping. Schram doesn't know who killed Kurtz, and he says he's no stoolie; Ness says he turned state's evidence once, to reduce his prison sentence. Schram points out the scar on the right side of his face, from his ear to his chin, that he got for squealing.
Next day, Kulak is impressed with Seegar, for rubbing out his own lieutenant; Kulak calls Seegar "his partner." Meanwhile, Roxie is having a red-hot affair with Seegar; he tells her that after the big meet in 10 days, he'll own the whole country. Schram shows up, begging for a job from Seegar; Schram also sees Roxie (who is still legally married to him) shacking up with Seegar. Seegar tells him there's no job for stoolies; Schram says he never squealed on him...he only squealed on the others because he couldn't face 20 years in prison. When Schram and Roxie are alone, she spells it out for him. They were only married "a month or 6 weeks" (funny that she doesn't remember exactly); Schram's been in prison for 3 years, and Seegar is spending a fortune on her, with diamonds, furs, etc.
Schram turns stoolie for Ness, to make a few bucks. 8 days later, Schram tells Ness about a meeting at Seegar's new apartment (rented by Roxie, which is why Ness didn't know about the apartment) on Beck Street: Jerry Tomack from L.A. and Corey from N.Y. will be there. Ness decides to put a wiretap in Seegar's apartment; he gets George Cooper, police technician to do it. But Kulak discovers the wiretap-- and Cooper listening in, down in the basement. When Ness doesn't hear from Cooper, he and Rico and Lee Hobson go to the apartment to investigate. A speeding car dumps a big trunk, containing Cooper's body.
Ness goes to the Athletic Club to question Seegar, and finds him there with Kulak. Ness demands to know where Roxie is, and Seegar quips she's out playing mahjong. After Ness leaves, Kulak fingers Roxie; either Seegar rubs her out, or the meet is off. Later, Roxie is driving her car, and Seegar's hitman Dutch is in the back-seat; he puts a knife to her throat. Roxie pleads for her life, saying "I could be nice to you." (with the strict 1961 TV censors, this implies a lot.) Roxie also offers him money not to kill her; finally, Roxie crashes her car, and escapes. Roxie goes to Schram, she says they will run away together. But then Roxie goes to Seegar and Kulak, and tells them it's Schram who's been talking to Ness, not her. Seegar sends his hitmen, Dutch and Boomer (who's ugly) after Schram; they kill him in a warehouse freezer room.
Thursday. Ness has Roxie hauled in; she says Seegar didn't kill George Cooper, Kulak did. Just before 11:00 a.m., 6 big bosses from all over the country meet at the Rathskeller with Seegar: Jerry Tomack from L.A., Arno Schwager from Cincinnati, Gil Corey from N.Y., Dell, Bouchard and Nicholson. Seegar wants to start the meet, but the others won't do a thing until the Teacher, Joe Kulak, arrives. Seegar swears Joe Kulak is coming; Arno Schwager ominously takes out a long knife and starts carving on the meeting table. Then someone shows up: it's not Kulak, but rather Ness, along with Lee Hobson. Ness says Kulak won't be coming, he's being held for the murder of George Cooper. One by one, the bosses all leave. Then Ness turns his back on Seegar and walks out. Seegar pulls his gun. Lee Hobson warns him, "Eliot!" Ness shoots Seegar, and Lee Hobson shoots Dutch.