Lt. Clay Saunders, who is working undercover to try to negotiate a peace treaty with the Paiute chief Keohawk, is sentenced to death by his commanding office who thinks he has committed treason. Saunders sends a letter to Lincoln, who sends a reply via telegraph to Ft. Kearney, Nebraska. The letter is then to be delivered by the Pony Express to Fort Churchill. Craig Garrett must complete the usual nine-day trip in only seven days in order to prevent Saunders' execution.; When Craig Garrett is sidelined with a back injury, his 11-year-old brother Davy must take an emergency message through a blizzard to the snowbound town of Drewsville, telling that a supply train is on its way.; A supposedly true story of how Buffalo Bill fooled robbers while riding for the Pony Express.