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, at a terrible price— the life of a woman Court cared for. Years have passed. 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 of time may have passed but the Gray Man hasn't changed. He isn't one to leave a job unfinished or a blood debt unpaid.