Act of treason : a Mitch Rapp novel
(Book)

When an al-Qaeda-style bomb attack on the motorcade of the Democratic presidential candidate, Georgia governor Josh Alexander, in Washington, D.C., a month before the November election kills the candidate's wife and several Secret Service agents, Rapp uses all the tools at his disposal to investigate the claim of the now discredited head of the protective detail that a mysterious figure in a red baseball cap set off the fatal bomb. Rapp soon finds that the motive for the outrage may be personal rather than political.