In 1860, when their widowed mother can no longer support them, six siblings are sent on the orphan train by the Children's Aid Society of New York City to live with farm families in Missouri.

Deeply unhappy about the separation of her family because of poverty, twelve-year-old Megan gradually finds contentment and purpose in her new home on the Kansas prairie with a kind and loving adopted family.

In 1861, while living with his foster parents at Fort Leavenworth, Kansas, twelve-year-old Mike Kelly and his best friend Todd Blakely join the Union army as drummer boys but their dreams of glory end when they experience the full horrors of war at the Battle of Wilson's Creek in Missouri.

Nineteen-year-old Frances Mary Kelly, herself an orphan train rider six years before, returns to New York and agrees to escort a group of orphans west to find new homes.