Fort Wallace, Colorado Territory: 1873 After reports of brutal Cheyenne attacks on small ranches, young Captain Marcus Cavanaugh and his men saddle up to intercept the renegade band. While they're gone, a grief-stricken settler takes matters into his own hands and ambushes an Indian camp, killing several braves. Angered by the cowardly slaughter of his people, Chief Silver Bear vows revenge by enlisting the neighboring Sioux and Arapaho nations to declare war on the white man. When regular patrols can't stop the raiding parties, Captain Cavanaugh volunteers to take his company of Quick Riders to wipe out the hostiles and head off a full-scale uprising. But in a predawn attack, the three nations surround Cavanaugh's troops camped on a small island in the Arikaree River. Pinned down by enemy crossfire and low on supplies, they fight to hold their ground in the bloody battle for... CAVANAUGH'S ISLAND.