Lee Miyeon had just been released from jail and planned to let her wild side out again. But all is stopped when her long-time friend appeared in front of her, giving Miyeon a mission which was to make a guy who was in a gang all happy again. It sounds dumb, but tell that to him. During her assignment, a mysterious guy pops out, making her throw away her cool attitude.

Three doctors; Luhan, Lay and Kris are known as the "Child Doctors" courtesy of their best friend Suyun. In her opinion, Suyun says that these men are childish indeed, but they can get serious sometimes. They look mature, but they are annoying on her part. She still loves them anyways.