Cassie and her brother Seth escape their tormenting stepfather to travel to California partly on the new Continental Railroad. Cassie plans to wed a man she has corresponded with, but never met. In her haste to leave, she hasn't told him Seth is coming and wonders if he will accept her twelve-year old, fun-loving sibling, and would he be the same person he had portrayed himself in his letters? Thoughts of her sister Lizzy who had left on a wagon train niggle at her mind. Can she find her in the vastness of California? Cassie grabs Seth's hand and begins their journey. Upon arrival in the frontier town of Green Grass, Cassie works through her relationship with Wes, a mining disaster, and begins a new school seeking to find a purposeful and happy life.