Orphan X by Gregg Andrew Hurwitz

The Nowhere Man

The book follows Evan Smoak, a former government assassin known as Orphan X, who has left his covert operations behind to become a vigilante helping those in desperate need. Operating under the alias "The Nowhere Man," Evan uses his skills to aid the helpless while trying to maintain a low profile. However, his past catches up with him when he becomes the target of a relentless adversary who knows his true identity. As Evan navigates a dangerous game of cat and mouse, he must confront his own moral code and the ghosts of his past to survive and protect those he has vowed to help.