The Collectors by David Baldacci
The Camel Club is back, and this time they're hot on the trail of a deadly conspiracy that is bigger than anything the U.S has ever seen. The movers and shakers of Washington D.C. are all abuzz when the Speaker of the House is shot dead at a cocktail party...and the assailant is never found. But when a Librarian of Congress suddenly and mysteriously dies a short time later, the Camel Club senses trouble. Before any of them can even say "conspiracy theory," John Carr (a.k.a. Oliver Stone), and Caleb Shaw, Milton Farb, and Rheuben Rhodes find themselves plunged into a world of covert operatives who won't think twice about making them disappear in order to see their plan reach its shocking end...