In 1910, New York socialite Olivia resists an arranged, socially advantageous marriage. The mysterious death of her sister Eleanor in Northern California is an unhappy but convenient excuse to go West. On the way, she is nearly drowned, and decides to hide her identity when she arrives in Mercy Falls.

In her diary, thirteen-year-old Hattie chronicles her family's arduous 1847 journey from Missouri to Oregon on the Oregon Trail.

In 1851 twelve-year-old Sarah is a free Black, happy living with her parents, grandparents, and brother on their own farm in Iowa; but her father has been bitten by the gold bug and wants to take the trail west to California, and after some argument it is decided that the grandparents will stay on the farm, but the rest of the family will go; the journey will be difficult and dangerous, but if they survive extreme weather, difficult terrain, illness,...