Dark Money tracks the influence of corporate money in contemporary politics in the United States. Using Montana as a case study, the film engages with the complex history that Montana state politics has with corporate influence. Starting with the Anaconda Copper Mining Company, Dark Money shows how the influence of mining corporations caused state legislators to relax mining regulations, which resulted in an environmental catastrophe in Butte, with problems that persist today. John S. Adams of the Montana Free Press plays a central role in the film as an investigative journalist who has been tracking state politics and following the money for several years. Adams has reported on everything from the role of the American Tradition Partnership (formerly known as Western Tradition Partnership) funds in the shaping of state election laws, to the illegal political activities of a "right to work" PAC in Montana. The film follows Adams's work as a reporter, but it also includes interviews from other prominent figures in Montana state politics and those involved in the movement to examine and limit the influence of dark money in politics.