The plot of a man, wondering alone, helping people, and good at fighting.
So that's what Jack Reacher is in the stories.
He used to have lord, the Army. Then he quit. He still have all the skills he learned while he was in Army. Now he wondering around his country, helping the less skillful to fight the good fight.
I finally completed the series and looking forward to the new one.
But after thinking how he behaved, and how he interact with women, he is certainly a ronin.