Hee Seong lives the best time of his life. He has a successful life as a metal craftsman with his beautiful wife, Ji Won, and a lovely daughter. One day, Ji Won, a detective, was assigned to investigate the attempted murder of a child while an unexpected visitor comes to Hee Seong’s workshop. This throws the couple’s life into turmoil and their happy moments start to fall apart.

A murder case similar to the Yeonju City serial murder case happened. 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.

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.

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.

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.

Hee Seong was brought to an emergency room without any consciousness. Luckily, he wakes up, but Ji Won heard something unexpected while Hee Seong was unconscious. After having a drink with a local cop in Gakyeongri and heard about the witness of Do Mis Seok’s last victim, Jung Mi Sook, Moo Jin tries to talk to witness to get to the bottom of the story.

Ji Won can’t clear up her doubts about Hee Seong, so she triggers him with the recording of Do Hyun Su’s voice and asks him to go to Do Min Seok’s workshop. When Hee Seong gets to the workshop, he panics and asks Ji Won to leave. Meanwhile, Hae Su meets up with Moo Jin and tells him that Do Hyun Su isn’t the actual accomplice.

Hyun Su asks Moo Jin to look for Hae Su in order to find the accomplice. During a stakeout, Ji Won encounters In Seo from an earlier case. Ji Won’s team gets to reinvestigate the Yeonju City serial murder. Meanwhile, Hyun Su finally meets Hae Su, and the three of them get together to find the accomplice.

Ji Won visits Moo Jin’s house and finds Hyun Su and Hae Su there. Hyun Su hurriedly tells Ji Won that he was helping Moo Jin’s investigation, but Ji Won gets more certain that her husband is Do Hyun Su. She ends up telling him that she doesn’t love him anymore. Hyun Su thinks the only way to turn things back to normal is to find the accomplice himself.

Hyun Su seals a deal with the human-trafficking ring run by Yeom Sang Cheol. His goal is to save the kid and retrieve information about Do Min Seok’s accomplice. He calls the police for backup in agreement for the big case. However, Ji Won feels anxious about Hee Seong’s every move and Hee Seong starts to think that Ji Won might know who he really is.

Knowing that Detective Choi found out about Hyun Su’s identity, Ji Won begs him to turn a blind eye on the case. Meanwhile, Hyun Su gets into trouble while undergoing a plan to find Do Min Seok’s accomplice. Just when Hyun Su is about to give up, Ji Won shows up and saves him. Although Ji Won forces Hyun Su to run away before it’s too late, he decides to stay because nothing is more important to Hyun Su than Ji Won.

Jae Seop meets Hyun Su and Ji Won and investigates Hyun Su. However, Jae Seop decides not to get involve with this and supports Ji Won’s decision. Meanwhile, Hae Su tries to turn herself in for the village foreman murder, but Ji Won stops her on behalf of Hyun Su. Hyun Su wants to confirm that the person who tried to kill him is Director Baek.

Hyun Su and Ji Won visit Director Baek’s house late at night. Fully convicted that Baek is the accomplice, Hyun Su corners him but unexpected events guide the couple in a different direction. Perplexed, Hyun Su receives a mysterious phone call one night. The next day, the dead body of Director Baek’s housekeeper is found in the mountains.

Hyun Su and Ji Won were gone when the police arrived at Hyun Su’s workshop. The only thing the police are left with is footage of Hyun Su’s threatening Ji Won with a knife. Meanwhile, Hyun Su shares his plans with Ji Won, which she disagrees, and manages to outsmart her so that she doesn’t further get involved. Hae Su is asked a favor to take care of Eun Ha. When they stop by Hyun Su’s house for Eun Ha’s belongings, Hae Su comes across an unwelcome guest.

The police find out how the autopsy doesn’t match with the last footage of Park Soon Young alive. They wind down and find out that she was long dead at Director Baek’s house. As an attempt to trick the culprit, they fake Hae Su’s attack as Detective Cha’s death and visit Director Baek’s house only to realize that Hee Seong and Hyun Su are together.

Hyun Su manages to survive the gunshot wound. However, he’s lost his entire memory with Ji Won. Meanwhile, Hae Su is brought to a trial for the murder of the village foreman, but Hyun Su testifies that it was only to defend herself. Ji Won eventually gives up on Hyun Su and decides to move on with her life. Hyun Su on the other hand does what he should’ve done the moment he returned to Ji Won.