Slocum needs to get out of St. Joseph, Missouri, thanks to a money-grubbing sheriff who fines him every chance he gets. When newcomer Ed Warren is held up, Slocum shoots the would-be robber, only to be levied yet another fine. But Slocum's luck turns after Ed offers him a job protecting a small wagon train hoping to strike it rich in the Colorado mines.

Just before the Rockies, they are attacked by a group of otherworldly creatures that rise out of the ground and can disappear into thin air. The creatures are led by Spirit Bear, who has sworn to kill anyone who crosses his land. In order to get the wagon train to safety, Slocum has to hunt down Spirit Bear, his most unearthly foe yet...