Pinkerton detective Maggie Cartwright is tasked with going undercover as a mail order bride. Her "fiancé" is widower Garrett Thomas, aka the suspected Whistle-Stop Bandit. No sooner does Maggie arrive in Arizona Territory when she's confronted with an early wedding date—the clock is ticking on her detective work or she may end up a criminal's wife! As the day of the wedding draws near, Maggie begins to panic. The problem is that the more she gets to know Garrett and his two adorable children, the harder it is to keep up the deception. Can a man as kind and gentle as Garrett really be the Whistle-Stop Bandit?