Wolfie and his older sister Dodo raise an orphaned horse after being forced out of their London home during World War II, but then the horse, Hero, is stolen and Wolfie finds him working in the mines under terrible conditions.
Forced to leave London for a new home in the country after their father refuses to join the military during World War II, Wolfie and his brother, Dodo, bond with an orphaned foal that they risk their lives to rescue.