During the summer in the present day, Jeon Youn Ha runs a vacation cottage located deep in the woods. His peaceful life is shaken by the sudden appearance of a mysterious woman named Yoo Sung A.

In the early 2000's, Koo Sang Joon ran the same vocation cottage as Jeon Young Ha did years later. Koo Sang Joon and his family also lived there, but, during the summer, something happened at his vacation cottage and Koo Sang Joon lost everything because of that. At that time, Yoon Bo Min worked as a police officer at the nearest police substation from the vacation cottage. 20 years later, Yoon Bo Min is transferred to the same police substation where she worked before and she begins to work there as the chief. She enjoys solving things and begins to observe Jeon Young Ha closely.