Mary Ellen Thomas is traveling west with Jenkins and his son to live with her remaining family. Her dad, Jenkins' business partner, has passed away leaving her an orphan. Because of her rough life and treatment by the Jenkins, Mary Ellen has developed a gruff attitude, especially toward adults. She is frequently in trouble and causes the Major and his men grief. She has one friend on the train: Sally Mayhew, who is dying from consumption. Her parents are taking her to Colorado for her health but have come too late to help her. Sally is confined to her wagon and Mary Ellen gives her a mouse for companionship. As a prank she puts it in a woman's sewing bag, but Mary Ellen is blamed. As they approach the Rockies, it becomes apparent it will be too late for Sally, so the Major decides to stop the train and have an early Christmas party for her. Sally is from Louisiana and Mary Ellen, knowing she wants to see snow, decides to go off for it on her own without letting anyone know. On the way she finds an Indian boy with a broken leg. Her actions put her into a scary situation, but for a change the end result pleases everyone.
—Anonymous