The story takes place inside an old library and revolves around a magical bookmark that allows people to travel back in time through the books. Six young individuals find themselves going on an adventure of a lifetime when they encounter each other in the library.

This story is about three people, Jae Ho, Shi Yung and Suk Ho. Jae Ho and his sister Jae Young are abandoned by their mother to escape poverty. Because of this, Jae Ho doesn't understand what love is. And so, he has a dream of becoming rich, thinking that there is no such thing as love, only money. He works hard his whole life while supporting himself and his sister through college. He works at a seafood wholesale market selling crabs to vendors. He lives with his aunt who has taken him and his sister in after their mother abandoned them.

With his big dreams and ambitions, he pretends to be rich while in school, in order to gain the attention of Hyun Su, who is from a very rich family. Thus, he tries to get her to like him so he can marry into her family and become rich. But during this process, he falls in love with his Psychology teacher, Shi Yung. He battles with his feelings and his ambitions, and ultimately picks love over money. Even though they go through hardship, he realizes that he couldn't survive without both, and so he gives up on Shi Yung for money and wishes her happiness.

Ep. 1 Tae Il is frustrated by her girlfriend's endless obsessions.

Ep. 2 Ji Won is sad when she's left out because her best friend gets a new boyfriend.

Ep. 3 Hye Joo can no longer keep her feelings for her old friend Sol to herself.

Will things ever go back to the way it used to be when everything was simpler?