"Before he was the Gray Man, Court Gentry was Sierra Six, the junior member of a CIA action team.
In their first mission they took out a terrorist leader, but at a terrible price--the life of a woman Court cared for. Years have passed and now The Gray Man is on a simple mission when he sees a ghost: the long-dead terrorist, but he's remarkably energetic for a dead man.
A decade may have gone by but the Gray Man hasn't changed. He isn't one to leave a job unfinished or a blood debt unpaid."