Follow the money. It’s one of the basic rules of investigative journalism, a catchphrase used throughout the Academy Award-winning film, All the President’s Men. The phrase also summarizes the methodology of a Montana journalist as he explores the proliferation of anonymous corporate contributions into American politics. Filmmaker Kimberly Reed in turn followed the story for six years while producing Dark Money, a political thriller with a touch of the Watergate movie’s intrigue, premiering on Nashville Public Television and PBS Monday, Oct. 1, on the POV independent documentary series.