The Lost Symbol (Robert Langdon, #3)

Robert Langdon, while at the U.S. Capital Building, finds an object encoded with five symbols, which is an ancient invitation to usher its recipient into a long-lost world of esoteric wisdom. When Langdon's belived mentor, Peter Solomon, is kidnapped, he realizes his only hope of saving Peter is to accept this mystical invitation and follow wherever it leads him. Langdon is instantly plunged into a clandestine world of Masonic secrets, hidden history, and never-before-seen locations - all of which seem to be dragging him toward a single, inconceivable truth.