Cavalry Sergeant Will Larson, part of a routine patrol on a four day ride, is ordered by the green patrol leader to ride down to the Rio Verde river. The river is a Chiricahua Indian stronghold, and Larson and his men are attacked and pinned down. When the patrol leader loses his head, the sergeant must take over - and heads out to hike seventy miles across the waterless desert to bring a relief column to save his comrades.