Dark Money: The Hidden History of the Billionaires Behind the Rise of the Radical Right is a 2016 nonfiction book by American investigative journalist Jane Mayer. The book examines the rise of secretive conservative funding in American politics, focusing on networks of wealthy donors like Charles and David Koch (the Koch brothers). It investigates how these billionaires and their allies have channeled billions of dollars into a web of organizations—including think tanks, advocacy groups, and political action committees—to shape policy, academia, the judiciary, and elections in favor of conservative and libertarian causes. Mayer draws on extensive reporting, including leaked documents and interviews, to expose the mechanisms of 'dark money'—undisclosed political spending enabled by post-Citizens United regulations—that allows anonymous contributions to influence democracy without public accountability. The narrative centers on the Koch brothers' role in building a parallel infrastructure (such as Americans for Prosperity and the Cato Institute) and also covers other key figures and families like the DeVos family and Richard Mellon Scaife, illustrating a broader ecosystem of right-wing philanthropy operating outside traditional campaign finance transparency. The book critiques how this system has amplified corporate interests, climate denial, and opposition to regulations, while influencing pivotal events like the Tea Party movement and Supreme Court nominations. Published by Doubleday, it received widespread acclaim for its rigorous journalism, became a New York Times bestseller, and sparked discussions on money in politics and calls for reform. It highlights the Donors Capital Fund as a key conduit for anonymous donations, underscoring the challenges of tracking influence networks in modern American governance.