Turn — Zack Mason

His friends are captured, and the President demands an audience... Mark Carpen has a shifter, a special watch that allows him to travel through time. He uses it to intervene in the past, rescuing the innocent from unforeseen violence and stopping tragic accidents before they can happen - though at times a mysterious force inexplicably blocks him, especially when he's trying to save someone he loves. Alexander Rialto is the leader of Dark Shift, a cabal of time-traveling assassins. Mark's mortal enemy, he is determined to exterminate the members of ChronoShift once and for all. While Rialto threatens to set the Middle East on fire unless the leaders of the free world turn Mark over to him, the members of ChronoShift embark on a search through time for the one object that can stop Rialto in his tracks. But how do you find something that's been missing for almost three thousand years?