Chan Young (No Joon Ho) and Yoon Hee (Kim Yeon Soo) are the seemingly perfect couple. After over ten years of marriage, they suddenly get divorced, much to the surprise of everyone around them. The reason for their separation is a big mystery. Even after their divorce, Chan Young and Yoon Hee continue to happily see each other as good friends. Their odd relationship comes to another crossroad when Yoon Hee's old friend Seon Young (Kim Hyun Sook) and her son move in with her.