Kim Sunggyu and Kim Myungsoo were poor brothers who lived with parents who didn't bother to look after them and even made them do all the housework. Due to his father's addiction for gambling, they were both sold to the Nam's to pay for his debts. 

Sungyeol is a librarian who spends most of his time in the front counter of the library while Myungsoo is a guy who love reading books. The library, that's where they met.