After a confrontation in a bar leads to two mobsters dead in self-defense, Sam and Dean Winchester embark on a path to rid Boston of the stranglehold that the Sicilian mafia and the Russian bratva have on it. Complicating this is their close friend, Castiel Novak, himself a low-level member of the Sicilian Shirley family organization, who is in far more trouble than he realizes. Meanwhile, Agent Victor Henriksen is on a mission to catch the perpetrator of a string of vigilante murders targeting Boston mobsters. Their paths spiral closer and closer until they collide in an explosion that will leave no-one unscathed.
(Supernatural Boondock Saints AU)