From Amazon:

Michelle Maxwell has just wrecked her promising career at the Secret Service. Against her instincts, she let a presidential candidate out of her sight for the briefest moment and the man whose safety was her responsibility vanished into thin air.
​Sean King knows how the younger agent feels. Eight years earlier, the hard-charging Secret Service agent allowed his attention to be diverted for a split second. And the candidate he was protecting was gunned down before his eyes. Now Michelle and Sean are about to see their destinies converge.
Drawn into a maze of lies, secrets, and deadly coincidences, the two discredited agents uncover a shocking truth: that the separate acts of violence that shattered their lives were really a long time in the making—and are a long way from over.

In the book box.