Baek Hee Sung and Cha Ji Won are a married couple with a daughter. Ji Won received an unpleasant relationship with Hee Sung's parents despite being together. Ji Won is a detective and investigating a case in which In Seo, a boy, got into an accident and pointed his father as the culprit. It's between their family issue as the boy witnessed a heart-wrenching sight of his father with another woman. 18 years ago, a murder case occurred where Baek Hee Sung lives as Do Hyun Soo. He was a suspect. Now, Reporter Kim Moo Jin unexpectedly met him in Hee Sung's Metal Craft Workshop without knowing his current identity. Hee Sung strangled Moo Jin and hid in the basement. Ji Won, the wife, has no clue about his husband's doings.
A murder case similar to the Yeonju City serial murder case happens. The victim’s thumbnail was missing, and she had a noose around her neck. Something seems off about the case and Ji Won tries to solve it. Meanwhile, Hee Seong finds out that Moo Jin had a plan to meet his informant, Soon Kil to get a tip. And Hee Seong decides to do something about it.
Something is Off
Ji Won feels something is not right when she saw Hee Seong coming home with a raincoat on in the middle of the night. The next day, Ji Won gets assigned another murder case and the surveillance footage shows that the victim got killed by a man in a raincoat. And all the evidence left at the crime scene points Do Hyun Su as the prime suspect.
The Real Culprit
Hee Seong gets baffled to become the prime suspect of Hoesin-dong Chinese restaurant murder case. Only Hee Seong and Moo Jin know that someone else is copying Do Hyun Su to pin the murder case on him. And Hee Seong and Moo Jin decide to work together to find out the person while Ji Won meets Do Hae Su, Do Hyun Su’s sister, to find more about the suspect.
The Watch Strap
A police officer hands over a watch strap as a piece of evidence from the crime scene in Gakyeongri to Ji Won. It is the strap that is engraved with Hee Seong’s initial on it. Ji Won instinctively feels something is wrong. And the owner of the inn calls the police to report that a taxi driver is beating up a passenger. Ji Won realizes that Hee Seong is somehow involved in the case.