Captain Phillip Donlin (Lloyd Bridges) and his small troop must rush to reach Little Big Horn in order to warn General Custer of the Sioux attack that awaits him. As they race against time, and Donlin pushes them hard through an arduous and dangerous journey, the Sioux start taking out the soldiers one at a time. Meanwhile, Donlin also clashes with Lt. John Haywood (John Ireland), who Donlin knows is having an affair with his wife, Celie (Marie Windsor).