The Fugitive — Max Brand

Stephen Macdona fled his home with only two possessions: his talent for survival and his prize mare, Christy. Before he can be charged with a killing he never meant to commit, he's south of the border with a new name. But it's Christy who attracts the most attention. As soon as Señor Don Rudolfo Alvarez sees her, he wants the horse for himself, and he'll do everything in his vast power to get her. What he doesn't know is that Stephen will go to any lengths to keep her....