In 1864, northern Kansas was being terrorized by southern sympathizers known as Copperheads, and gambler Frank Graham goes to Junction City seeking the killer or killers of his father. He gets little help from Union Army officers Colonel Barnes or Captain Ramsey, but gets a job at the freight line co-owned by Jane Dudley and his late father. Jane tells him his father was stabbed in a quarrel over counterfeit money given to him for his freight interests. Frank learns that Hardy, a printer; Temple, a store owner; Perry, a peddler; Greeley, a gambler, and Spain, a jeweler, are Copperheads and one of them murdered his father.