US Marshal Penny Larkin was certain about three things. First, she was over her romance with Sheriff Leo Tellez who had been unfaithful. Second, she had lost her nerve to fire her gun again, after killing two fugitives in self defense. And third, she never wanted to face another Mexican drug cartel. When a New Mexico quarter horse trainer asks Penny to investigate a rash of barn fires endangering his pregnant mares, she is horrified to discover a Mexican drug cartel has infiltrated America's quarter horse racing industry. Not only is Penny forced to use her gun again, she must also find a way to escape not one, but two barn fires, and then douse a fire of her own making-her adamant refusal to take another chance on love.