Oscar Wallace, Eliot Ness, Jimmy Malone, and George Stone, the four main members
The Untouchables were a task force of US Department of the Treasury special agents led by Eliot Ness who, from 1930 to 1931, worked to bring down Al Capone and his Chicago Outfit's illegal activities. The force was given its nickname by corrupt alderman John O'Shea, who criticized them for being "untouchable" after Ness refused to accept his bribes. The incorruptable squad carried out raids against the Outfit's liquor stashes and shipments, began an investigation against Capone for income tax evasion, and convinced some members of his organization to turn states against him. Ultimately, team members Oscar Wallace (who came up with the tax evasion investigation idea) and Jimmy Malone (a veteran CPD offier and Ness' mentor) were killed by Outfit hitman Frank Nitti during their campaign, but Ness and George Stone were able to ensure that Capone was sentenced to 11 years for tax evasion after securing the vital testimony of his chief bookkeeper, Walter Payne. After Capone's trial ended in 1931, Ness returned to his family, while Stone returned to the CPD.