Split Second by David Baldacci
Secret Service Agent Sean King's career is destroyed when the presidential candidate he is protecting is assassinated. Eight years later, King had worked hard to rebuild his life until he arrives early to work to find a body in his law office. Meanwhile, another secret service agent, Michelle Maxwell's, career is similarly destroyed when her protectoree is kidnapped. Somehow the cases are connected and the bodies are piling up. King and Maxwell team up to solve the mystery before they are killed themselves.
I thought this was a great thrill ride that kept me guessing until the end! I will definitely continue the series.