As long as she can remember, Areum always had dreams about a girl about her age. She has no idea who this girl is, but when she sees the picture of that girl in her grandmother's album, the dreams come to an end, and Areum travels to another time period. That is when she meets Eun-Kyung, the girl in her dreams. But the questions are, why and how did Eun-Kyung travel through time? Could Areum and Eun-Kyung return to their regular time periods after accomplishing their mission?