Laura Rose White's late father taught her everything he knew about piloting a Missouri River steamboat. He even named their boat after her. Despite that, it seems that Laura will forever be a "cub pilot" to her brother Joe, because in 1867, a female riverboat captain is unheard of. That is, until tragedy strikes and Laura must make the two-month journey from St. Louis to Fort Benton and back in order to save her family's legacy, her home, and the only life she's ever known.

The only way for her to overcome the nearly insurmountable odds is with the help of her brother's disreputable friend Finn MacKnight, a skilled pilot with a terrible reputation. Laura loathes having to accept MacKnight as her co-pilot, especially when she learns she must also provide passage for his two sisters. Straight-laced Fiona has a fear of water, and unpredictable Adele seems much too comfortable with the idea of life in the rough and tumble environment of the untamed river and the men who ply it. Though they are thrown together by necessity, this historic journey may lead Laura and the MacKnights to far more than they ever expected.