Captain Tom York is dispatched to contact General Custer at Little Big Horn. There he finds the massacred 7th Cavalry and thousands of Sioux roaming the Black Hills. He rushes to warn the other regiments heading for Custer's location but needs to find a telegraph office in the nearest town. That town is Deadwood. The townsfolk seem oblivious to Custer's fate and to the fact that thousands of Sioux are coming their way. The telegraph is out of order and the locals mistake Captain York for a deserter. After a friend, Ep Wyatt, vouches for him, the misunderstanding is cleared up. York gets wind that big man Columbus Smith, whom York had a fistfight with, has a pair of Gatling Guns hidden nearby. When York and Ep Wyatt approach Smith, he reveals that saloon beauty and roulette dealer Dakota Lil McCoy actually owns the guns. In the saloon, Lil initially denies having Gatling Guns but eventually relents to the demands to surrender the guns at Captain York's request. The captain figures that a pair of such guns could save the day for the remaining Cavalry regiments heading toward the Sioux. However, getting the weapons is only half the dilemma, since the townsfolk argue that such guns would be better left in Deadwood to help defend the town against a possible Indian attack. Some town ruffians manage to the wrest the guns from York but he recovers them after a gunfight in which he's helped by Columbus Smith and Ep Wyatt. The trio loads the machine guns into a wagon and plan to pass undetected between numerous Sioux war parties camping on the Black Hills. They must deliver them in time to the incoming Cavalry regiments who have no clue about Custer regiment's annihilation or the exact strength of the Sioux army.