Following the massacre of General Custer and the 7th Cavalry at Little Big Horn, Army Captain Tom York rides into nearby Deadwood to warn the townspeople that the rampaging Sioux may attack. York is suspected of being a deserter until gunfighter Ep Wyatt identifies him as a special agent of the Army. Two huge Gatling guns are buried somewhere in the town, but only Dakota Lil of the local dance hall knows where, and she refuses to disclose the hiding place, claiming that they have already caused enough tragedy, including the deaths of her husband and little boy. York persuades her that the guns are vital to warding off an Indian attack, and she eventually leads him to where they are buried. Before they can be assembled, however, they are stolen by Elkins, a gambler who intends to sell them to the Sioux. Banded together by York, the townspeople kill Elkins, build barricades, mount the Gatlings, and prepare for the attack. York, Wyatt and old Columbus Smith ride off with the Gatlings to help a cavalry troop pinned down by the Sioux. Although Smith is killed, cavalry troops are found, and the Sioux quickly scatter. With peace restored, York decides to settle down in Deadwood with Dakota Lil.
