When twins Sarah and Julie feel like their mom is tired of them, they take off on an exciting adventure to their great-grandmother's house and encounter a pair of villains along the way.
Margaret Reed, a wealthy and proud woman of Chicago unwillingly finds herself a member of the Donner party - a group of pioneers making their way to California by covered wagon in the summer of 1846. One by one the odds begin to stack against Margaret and her family as precious days slip away and an early winter storm closes the passes through the Sierra Nevada mountain range. Trapped without adequate food and supplies, Margaret struggles to keep her family alive.
