"I am only a girl, not a fighter. But I would not wage war on women or old men," said Joan. Danny Morgan uncovered, stared at her with open admiration, then stuttered, "Neither will I. I'm with you." "Thunder" Flint, cattle king, had reached a cruel resolve, to drive the Nestors out of the country. To "Sweetwater" Sims, their leader, he sent warning, delivered by Danny to Joan, daughter of the Nestors. Flint sends the foreman to find "Cheyenne" Harry for "the work." Harry is found asleep in a saloon, where everyone is afraid of him as a "gunman." Harry agrees to meet Flint in Diablo. At their rendezvous near Diablo, Black-Eyed Pete and his gang are splitting the spoils of a marauding expedition. Harry meets two of the outlaws, who tell him they are cached up near the Big Rock. They seem to be friends. Danny and Ted, "Sweetwater" Sims' son, enter the saloon at Diablo together. There they come upon Harry, who, hearing that Ted is a Nestor, begins insulting him and shoots at both of them, but they escape. Flint does not place all of his trust in "Cheyenne" Harry, and sends for "Placer" Fremont, a gunman of unsavory reputation. Fremont and Harry meet at the saloon; each is suspicious of the other; each handles his gun while he drinks. Flint enters and sizes up the situation. Harry asks Flint if Fremont is another "killer" he has imported. Flint introduces Harry and Fremont, who merely extend a casual greeting. Flint is surprised and assures them that there is no cause for trouble, as they are both on the same job and there is plenty of work to be done. Ted and Danny ride to the cabin to tell Sims that Flint's "killers" have arrived and to prepare for trouble. Joan is greatly agitated. The next day Ted goes for a bucket of water and finds a sign warning the public that the spring is private property and that trespassers will be shot on sight. Fremont, hidden in a tree, raises his rifle and fires at Ted, who rolls down the bank, dead. Joan tells her father where Ted has gone; they rush to the spring and are grieving over the body of the boy when Harry rides by. The father tells Harry that he supposes he is one of the "killers," come to gloat over their "dirty work," but Harry insists that he did not know of their trouble, that he is a man and doesn't make war on children and old men. Harry tells Joan that if this is a sample of the work he was brought here for he's through, and from now on she can count on him whenever she needs him. Harry later informs the foreman that he's through with Flint and his outfit. When Flint hears that Harry cannot be depended upon, he sends Fremont to Diablo to "get" Harry. But Danny, hearing these instructions, warns Harry, who lays for Fremont, and in the act of being shot, kills Fremont. Flint and his gang start out that night. Danny has told Sims and Joan of the coming raid, and the girl rides out to warn all the Nestors, who ride from all directions to the cabin. Harry meets Joan and tells her that there are so many of the raiders that unless they get help they are lost. He rides to the camp of Black-Eyed Pete, where he asks for help. The outlaws rush to the battle, arriving in time to save the Nestors. The next day while Joan is caring for Danny's wounds, Sims asks Harry to remain at the cabin, but Harry declines, saying that there is something "just over yonder" which keeps calling to him. He tells Sims that he will let them know at sundown. Danny comes to him as he is thinking out his problem. Harry tells him to go back to the little girl. Joan is disappointed at first to see Danny instead of Cheyenne, who is left facing the setting sun alone.