The daughter of a poor rancher, Si-eun only hopes to become a horse racer. ‘Thunder’. With her mother passing away on her birth, ‘Thunder’ has become not only her friend, but a soul mate. Her life is devastated when ‘Thunder’ is sold to another owner, but two years after, they reunite by sheer coincidence. Now they have a chance to create a miracle by teaming up together in a horse race.