Like many a veteran of the Civil War, Cap Mackenna went west to the Rockies to build a new life. But that new life is changed forever the day he comes across an abandoned infant, whom he takes in and cares for until the baby's Cheyenne mother appears at his door. Alone and terrified, all the woman wants is to find the baby's father. Cap helps her locate him at the U.S. Cavalry encampment, but Colonel Tom Sully stands defiantly between the father and his family. When the desperate man deserts to be with his wife and child, Sully sends a detail after him and suddenly Cap finds himself caught in a deadly pursuit—ready to risk all for what he knows is right.