Susan Cameron, a young Missouri woman, arrives in Wyoming Territory determined to homestead on her own. Her nearest neighbors, Ellen Watson Averell and James "Jimmy" Averell, operate a small road ranch not far from the Oregon Trail on homestead land formerly grazed illegally by Albert Bothwell's cattle. Ellen purchased a small herd of cattle and brand, but Bothwell claimed the Averells were operating a rural brothel and that Ellen took calves for her "favors."
Trouble haunts Susan, her veterinarian friend, Michael, and the Averells from the moment Susan attempts to take possession of her new homestead land, culminating in the hangings of both Ellen and Jimmy Averell by six prominent cattlemen, who then spread vicious lies in their controlled Cheyenne newspaper, calling Ellen "Cattle Kate." The mystery deepens when the cattlemen are brought to trial and all the witnesses to the hangings have died or disappeared and Susan and Michael are kidnapped by hired gunmen . . .
