Swept up in the tumult of post-war 1919 and amid the rising tide of immigrants, virulent socialists, labor union strikers and discontented WWI veterans, Boston's primarily Irish police force does the dirty work to keep the city from gecoming unglued with long hours, paltry pay and little recognition. In Ireland, the Republican Brotherhood wages a guerilla war of independence with England, supported by Boston's Irish neighborhoods. Frustrated by political promises, Boston's guardians go on strike for better pay and working conditions. And as the city erupts, Willie Dwyer's nemisis crosses an ocean and comes to hunt him down.