General Kearny, an American commander in California, finds that he and his men are trapped by Spanish forces thirty miles from San Diego. The general sends an Native American youth, Lieutenant Beale, and famous mountain man Kit Carson across the harsh desert to San Diego to request aid. The three men encounter great difficulties on their journey: Spanish sentries, lost moccasins, lack of food and water, and illness. Prior to reaching San Diego, the three split up to increase their odds of successfully delivering the message for help. The Native American youth and Lieutenant Beale deliver their messages and wait in anticipation for their friend Kit Carson, who took the most difficult leg of the journey. To their great relief, they learn that Carson safely reached San Diego.