When the new marshal in town needs volunteers, one of the first to sign up is Miss Rosie Decker. And why wouldn't she? She's a sharpshooting, horse-taming tomboy—and she's out for revenge. Marshal Hank Walker is forming a posse to find the man who killed her sweetheart, and Rosie is determined to help track him down. When the marshal refuses her service on account of her being a woman, Rosie is undeterred. If it's a man Marshal Walker wants, it's a man he'll get. With his posse assembled, Hank Walker is confident he'll be able to track down the criminal. His confidence grows as he recognizes the incomparable skill of one young man in his posse—Ross. That is, until the day Ross's mustache falls off, revealing "his" true identity. Rosie Decker has duped him. Banished back to town, it's time for Rosie to prove her mettle. Though working alongside the unwilling marshal is complicated, it is the unexpected tenderness she feels for him that proves most problematic. How can she demonstrate her skill while also setting out to win the heart of the man who seems bent on keeping her out of his way?