In 1930, during
Prohibition, the notorious gangster
Al Capone supplies illegal liquor and controls most of
Chicago.
Bureau of Prohibition agent
Eliot Ness has been tasked with halting Capone's activities, but his first attempt at a liquor raid fails due to corrupt policemen alerting Capone. He encounters veteran
Irish-American officer James Malone, who opposes the rampant corruption and offers to help Ness, suggesting that they find a man from the police academy who is not yet under Capone's influence and still believes in the idealistic aspects of law enforcement. They recruit Italian-American trainee George Stone (born Giuseppe Petri) for his superior marksmanship and integrity. Joined by accountant Oscar Wallace, they successfully raid a Capone liquor warehouse and start to gain positive publicity, with the press dubbing them The
Untouchables. During an organizational dinner team meeting, Capone kills the warehouse manager with a
baseball bat to warn his other subordinates. Discovering that Capone has not filed an
income tax return for four years, Wallace suggests trying to build a
tax evasion case against him, as Capone's network keeps him well insulated from his other crimes. Crooked
alderman John O'Shea offers Ness a bribe to drop his investigation, but Ness refuses. After Capone's enforcer
Frank Nitti threatens Ness' family, Ness immediately moves his wife Catherine and daughter to a safe house. In a subsequent raid on the
Canadian border, Ness and his team intercept an incoming liquor shipment, killing several gangsters and capturing a Capone
bookkeeper named George, whom they eventually persuade to testify against his employer. Back in Chicago, Nitti, dressed as a policeman, murders Wallace and George in the elevator of the police station and leaves a taunting message for Ness. Ness confronts Capone at the
Lexington Hotel after the murders, but Malone intervenes, urging Ness to focus on persuading the
district attorney not to dismiss the charges against Capone. Realizing that police chief Mike Dorsett betrayed Wallace and George, Malone forces Dorsett to reveal where Capone's accountant Walter Payne is hiding. That evening, one of Capone's men breaks into Malone's apartment. Malone chases him with a shotgun, but Nitti ambushes him with a
Thompson submachine gun. Shortly afterward, Ness and Stone arrive to find Malone mortally wounded. Before he dies, Malone shows them which train Payne will take out of town. As the duo await Payne's arrival at
Union Station, Ness notices a young mother with two suitcases and her child in a carriage laboriously climbing the lobby steps. Ness ultimately decides to assist her, but the gangsters guarding Payne appear as Ness and the woman reach the top of the stairs, and a bloody shootout occurs. Although outnumbered, Ness and Stone manage to capture Payne alive and kill all his escorts, keeping both the mother and child unharmed. When Payne testifies at Capone's trial, Ness observes that Capone appears strangely calm, and that Nitti is wearing a gun in the courtroom. The
bailiff removes Nitti and searches him, finding a note from Chicago Mayor
William Hale Thompson that effectively permits him to carry the weapon. However, noticing that Nitti possesses a
matchbook with Malone's address written inside, Ness realizes that Nitti killed Malone. Panicked, Nitti shoots the bailiff before fleeing to the courthouse roof, where Ness captures him. After Nitti insults the memory of Malone and gloats that he will escape conviction for the murder, an enraged Ness pushes him off the roof to his death, avenging Wallace and Malone. Stone gives Ness a list, taken from Nitti's coat, which shows that the jurors in the trial are all on Capone's payroll. Ness secretly persuades the judge to switch Capone's jury with one hearing an unrelated divorce case. This prompts Capone's lawyer to enter a guilty plea, although an outraged Capone violently objects. Capone is convicted of tax evasion and sentenced to 11 years in prison. On the day of his sentencing, Ness closes up his office, giving Malone's
St. Jude medallion and callbox key to Stone as a farewell present. As Ness leaves the police station, a reporter asks him what he will do after the probable repeal of Prohibition, to which he replies, "I think I'll have a drink". ==Cast==