The Gray Man by Mark Greaney. Published 2009 ***This book contains strong language***
The following summary was obtained from Goodreads.
Courtland Gentry is a good man. But he’s a great assassin. To those who lurk in the shadows, he’s known as the Gray Man. He is a legend in the covert realm, moving silently from job to job, accomplishing the impossible and then fading away. And he always hits his t…