Since giving up his life as a government assassin, Robert McCall has struggled to reconcile the horrific things he's done in the past and finds a strange solace in serving justice on behalf of the oppressed. Finding himself surprisingly at home in Southern Italy, he discovers his new friends are under the control of local crime bosses. As events turn deadly, McCall knows what he has to do: become his friends' protector by taking on the mafia.

Vigilante Robert McCall is continuing his life of helping ordinary citizens find justice in everyday situations before a close friend of his is murdered by a mysterious group of criminals for seemingly no reason. The plot shifts as he then makes it his goal to find out what happened to his friend and deliver justice on her behalf, sending him on a wild goose chase to figure out who these people are, why they would harm his friend, and if there is...