In 1927, Prohibition agent Eliot Ness narrowly escapes a hit ordered by Al Capone. Determined to prove to Capone that he's not intimidated, Ness and his team of Untouchables execute a series of high-profile raids on Capone's breweries. Over the course of a few months, they destroy more than 200,000 gallons of beer, worth a modern-day equivalent of $134 million - and the newspapers cover it all.
To culminate his crusade, Ness has one more move. In a brazen display of defiance, Ness gathers the bootlegging trucks he seized form Capone and parks them right outside the Lexington Hotel.
Capone lashes out against Ness in the press. What Capone doesn't realize is that Ness and the Prohibition agents aren't the only ones trying to take him down. For the past four years, another government agency with more manpower and resources than Ness has been going after the infamous kingpin: the IRS.
Leading the IRS investigation is Frank Wilson, an accountant known for his meticulous attention to detail. Despite his relentless efforts, Wilson is unable to find concrete evidence of Capone's income. However, he has a secret weapon: Mike Malone, an undercover agent working within Capone's organization for the past two years.
With his every move being tracked without his knowledge, Capone remains focused on stopping Ness' raids. After paying off local telephone companies, he wiretaps Ness' phone lines and learns of an upcoming raid on one of his breweries. When Ness raids the brewery with reporters in tow, the brewery is already empty. Ness is left humiliated.
Meanwhile, Wilson has yet to find anything that directly links Capone to his illegal rackets, despite months of analyzing evidence. So he targets the gangster's inner circle and finds a personal bank account owned by Capone's head of finances, Frank Nitti, showing hundreds of thousands of dollars in untaxed income. Nitti is arrested and sent to jail for tax evasion. His absence hurts Capone's organization.
On Capone's orders, Capone's men come up with a plan to take out Wilson. Malone warns Wilson of the hit, saving his life.
Following a tip from Malone, Wilson begins combing through thousands of evidence boxes collected over the four-year investigation into Capone. He finds a ledger seized during a raid on one of Capone's casinos and discovers a page that actually has Capone's name on it.
With Capone's name on the ledger, Wilson can at last connect the mob boss to his illegal operations. On June 5, 1931, Capone is indicted for tax evasion. After paying the modern-day equivalent of a quarter-million dollars for bail, Capone walks free.
Determined not to let the IRS steal his spotlight, Ness hits Capone a week later with 5,000 bootlegging charges. As news of the charges begins to make headlines, Capone's public image falters. Yet the mob boss remains unfazed, causing concern within his organization.
Using their connections at City Hall, Capone's gang acquires the names and addresses of every member of Capone's jury for the upcoming tax evasion trial. The Outfit begins a campaign of bribery and intimidation to persuade the jurors to side with Capone.
On the morning of the trial, October 6, 1931, Capone is confident he has all the jurors on his side. At the last minute, however, Judge James Wilkerson switches the jurors for another set of jurors, foiling Capone's plan. As the trial unfolds, witnesses testify to Capone's extravagant spending. Each new revelation about his decadent lifestyle attracts national headlines.
The prosecution finally reveals its key piece of evidence, the ledger, tying Capone directly to thousands of dollars in hidden income. Testifying against Capone is the bookkeeper who filled out the ledger.
After only 17 days of testimony, the jury finds Capone guilty. On October 24, the court sentences him to 11 years in prison with fines of $50,000 - the maximum time on all charges and the harshest tax evasion sentence in American history.
Meanwhile, the case against Capone for prohibition violations, considered much weaker, is never pursued. Ness realizes that he won't be the one to take down the Chicago mob boss.
While Capone's lawyers work on his appeal, the kingpin continues running his empire from the inside, even paying off the prison warden so that he can enjoy the comforts of home. When Judge Wilkerson gets word that Capone is receiving preferential treatment, he strips Capone of all his comforts in jail and cuts him off from his empire entirely. Capone's final appeal is rejected and the government orders him to be transferred to a federal prison in Atlanta. As he awaits his transfer, Capone asks his top lieutenants, Paul Ricca and Tony Accardo, to run the Outfit until he gets out.