The Fenians, an Irish Revolutionary Brotherhood, are trained soldiers sworn to free Ireland from British rule. The Fenians have gathered in Dakota City to plan a march into Canada where they want to take hold of a small part of British property hostage in exchange for Ireland's freedom. After England pressures the United States to intervene, Beau Maverick is blackmailed into infiltrating the Fenians ranks by a shrewd Army colonel. (thetvdb.com)