In a special investigation in collaboration with Marketplace, FRONTLINE travels to the remote epicenter of the campaign finance debate for a tale of money, politics, and intrigue. How has the Supreme Court’s Citizens United decision changed campaigns in America? Ask Montana, which has tried to challenge the ruling in court, is investigating alleged campaign abuses, and is playing host to a bitter race that could decide control of the U.S. Senate.FRONTLINE correspondent and Marketplace host Kai Ryssdal reports.