The story unfolds during the tumultuous era leading up to the American Civil War, focusing on a group of young men graduating from West Point in 1854. Among them are Jeb Stuart and George Custer, who are assigned to safeguard efforts at providing new routes for the Santa Fe Trail, amidst escalating tensions over issues of slavery. Their assignment leads them to confront John Brown, a fervent abolitionist whose radical actions ignite divisions in the states. Brown's violent crusade against slavery culminates in a raid against pro-slavery settlers in Kansas, pulling Stuart and Custer deeper into the volatile clash between abolitionist forces and pro-slavery interests. Their duty entangles them in skirmishes and ideological battles that mirror the fracture threatening the nation.

Alongside political conflicts, personal relationships evolve, including a developing romance involving Stuart with Kit Carson Holliday, the daughter of a train magnate also tied to West Point through familial connections. The presence of the charismatic Custer thickens this interpersonal dynamic, weaving together issues of loyalty, ambition, and morality amid growing tensions. As they navigate their responsibilities and relationships, the consequences of Brown's relentless campaign against slavery come to a head. The film explores themes of duty and honor against a backdrop of national discord, setting the stage for further confrontations that underscore the complexity and inevitability of the looming civil strife. Through these intertwined narratives, characters grapple with their roles in history at a pivotal moment for America.