During a total eclipse of the sun, a 25-year-old 21st century woman, Ko Ha-jin (Lee Ji-eun), drowns and is transported back in time to Goryeo Dynasty Korea. She wakes up in the body of 16-year-old Hae Soo and there, she encounters the many royal princes of the ruling family. She falls in love with 8th Prince Wang Wook (Kang Ha-neul), and then for Wang So (Lee Joon-gi), the fearsome 4th Prince who hides his face behind a mask and is given the derogatory label "wolf dog" by the others.