Following the death of their parents, twenty-four-year-old Sunniva Lyndall and her younger brother, Tracy, leave the comforts and safety of their Ohio Valley home to travel west to California. With excitement, determination, and the money they received from the sale of the family farm, they head for Missouri and the wagon train that will take them west. But Sunny and her brother quickly learn the ways of the West the hard way when a con-man swindles them out of their money. Without means to buy supplies, California seems out of the question. Employment with the Pony Express seems to be the only available option. With Tracy as express rider and Sunny as station manager, it looks like they will soon earn enough to resume their journey. But unplanned adventure in the saddle of the Express awaits Sunny with the greatest challenge of her young life.