In reading order
The Gray Man
Mark Greaney
On Target
Mark Greaney
Ballistic
Mark Greaney
Dead Eye
Mark Greaney
Back Blast
Mark Greaney
Gunmetal Gray
Mark Greaney
Agent in Place
Mark Greaney
Mission Critical
Mark Greaney
One Minute Out
Mark Greaney
Relentless
Mark Greaney
Sierra Six
Mark Greaney
Burner
Mark Greaney
The Chaos Agent
Mark Greaney
Midnight Black
Mark Greaney
The Hard Line
Mark Greaney
Dark Union
Mark Greaney