Harry Truman and Herbert Hoover were from opposing parties, but they became friends when Truman took office after Franklin Roosevelt's death and needed some advice. This was the start of the presidents club, a shadow organization that began as a joke. These private relationships — and rivalries—among the most powerful men in the country are documented in Nancy Gibbs' and Michael Duffy's new book "The Presidents Club: Inside the World's Most Exclusive Fraternity." Gibbs and Duffy trace the evolution of the presidents club from the end of World War II to Barack Obama. They spoke at Seattle's Town Hall on May 11, 2012.