With the Civil War behind them, President Lincoln, James Griffith portraying Abraham Lincoln, selects Indian scout James Kingston, Bill Williams to shepherd a northbound cattle drive from Texas to ease the meat shortage in the Northeast. He is joined by Ray Teal as Sgt. Tim O'Roarke and Don C. Harvey as Maj. Donald "Tex" McGuire. The plan is to push a long wagon train of cattle through hostile territory—Confederate sympathizers and Apache bands—toward Abilene, Kansas. Hidden within the convoy is a cache of Henry repeating rifles, secretly shipped by Hank Calvin, a merchant played by Ray Corrigan. The promise of these rifles could tilt the balance of power on the frontier.
Into this fragile alliance comes Joaquin Jironza, Alex Montoya a Mexican bandit who works with the Apache and wants the repeating rifles for himself. He is opposed by Lee Parker, Richard Jaeckel, a bitter one-armed ex-Rebel traveling with the train and a potential obstacle to Kingston’s mission. A female spy working for Jironza has befriended Calvin and learned about the rifles, then slips away to relay news of their location to the bandits.
When Jironza and his Apache allies strike, the wagon train fights back with the recovered rifles. The attack is repelled, but Hank Calvin is killed and the secret of the rifles is exposed to everyone. The wagon train reaches San Arturo, yet the rifles themselves vanish, fueling suspicion and panic. To make matters worse, the Union Army cannot supply the promised escort because the War Department orders Kingston to shift focus to the Mexican border, leaving San Arturo and the convoy exposed to rising tensions between Union and Confederate sympathizers.
As suspicions flare, it becomes clear that Parker knows where the rifles are. A confrontation erupts in town as Kingston and his men search for the missing weapons, while Parker, protected by his father, slips away and is captured by Jironza. Parker offers to reveal the rifles’ location in exchange for protection for his father and sister, Ann Parker Adelle August, and to disrupt the cattle drive. In a chance encounter, Kingston discovers the rifles buried beneath Calvin’s wagon, lifting the veil on the conspiracy.
Jironza and his men attack the town again, and Parker is mortally wounded by the Mexican bandit, dying after asking Ann to warn Kingston that the Apache plan to ambush the herd at Carney Pass. The Apache stampede the cattle, but Kingston arrives in time to turn the herd away from the ambush, and the Apache chief is killed in the ensuing clash. The remaining tribes withdraw, and Kingston’s outfit presses on toward Abilene as planned. In the end, Kingston honors his promise to Ann, vowing to return after guiding the herd to safety.
