Nemesis

No greater friend. No deadlier enemy.
The explosive new novel in the New York Times bestselling Orphan X series is flipping the acclaimed series on its head. Find out why series superfans and new readers alike are calling it a "knockout" (firstCLUE).
Evan Smoak is a highly trained former government assassin who has survived for years by keeping his circle to a few trusted confidants and a strict code he calls "The Ten Commandments." But when Evan suddenly finds himself at odds with his oldest friend, all the rules he lives by shatter-and the consequences are murderous.
Tommy Stojack might be Evan's best friend in the world. He's a gifted gunsmith who has created much of Evan's own weapons and combat gear. But now, he has apparently crossed one of Evan's hardest lines and their argument explodes into open warfare. Now Evan has no choice but to track and face down his only friend.
In the meantime, Tommy has left town in order to honor his own promise to help a dead friend's son. While Tommy is fighting to save the son with everything he's got, Evan arrives with vengeance in mind.
But as deadly as the former Orphan X is, there is an even more dangerous threat about to arrive on the scene. The only question left is will any of them get out alive.

Gregg Hurwitz