For decades, Clover Connell and his Green Kern Gang have run the streets of Boston, both feared and beloved by the Irish of the city. Only Father Patrick Bradley, whose complicated history with Clover dates back to their childhood in Ireland, dares to stand up to them to protect his flock-especially "The Savios," a group of five teenage boys named after Saint Dominic Savio, patron of altar servers...and juvenile delinquents. Father Patrick has spent years trying to keep them off the streets and away from a life of violence.

But when the Savios's leader, Cullen O'Reilly, needs a way to provide for his pregnant girlfriend and their child, he turns to the Kerns, a sure path to money and power-until his father is murdered by Clover's men. Cullen embarks on a crusade of revenge and enlists the other boys to help. The Savios ignite a street war, using guerrilla tactics to bring down the Kerns with the help of a Boston cop who has his own score to settle. When the bloodshed spills into the ghettos of Belfast, the boys become embroiled in the Troubles of Northern Ireland, finding themselves targets of the IRA.

The Savios dives into the dark underworld of the Irish mob and the hostile conflict that erupted in Northern Ireland in the late 1960s. It is a story of vengeance, loyalty, family, and the battle that rages for the souls of violent men and the boys they raise.