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 Second Kansas Infantry in 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. When Todd dies in battle, Mike travels to the front lines to keep a dangerous promise: to return Todd's watch to his sister.