Conjoined twins Sang-hyun and Dong-hyun have lived for 30 years in a remote house alone with their father, who never allows them to go outside. Unlike obedient Sang-hyun, Dong-hyun is unhappy with his life and dreams of publishing a book one day. Their father finally decides to ask Seung-ah, a bright and kind caricature artist, to help Dong-hyun with the children's book he's writing. However, things slowly begin to change when both Sang-hyun and Dong-hyun fall in love with Seung-ah.