Heesung and Jiwon are married and they have a daughter. Jiwon is a detective and is investigating a case on a boy named Inseo, who got into an accident, and pointed his father as the culprit.

A murder case similar to the Yeonju City serial murder case happens. The victim's thumbnail is missing. Something seems off about the case and Jiwon tries to solve it.

Jiwon feels something's off when she saw Heesung coming home with a raincoat on in the middle of the night. Jiwon gets assigned another murder case, surveillance footage shows that the victim got killed by a man in a raincoat.

Jiwon spots a watch strap that is engraved with Heesung's initial at the scene and is in shock. And the owner of the inn calls the police to report that a taxi driver is beating up a passenger.

Heesung was brought to an emergency room unconscious. Luckily, he wakes up but Jiwon heard something unexpected about the witness. Moojin tries to talk to the witness to get to the bottom of the story.