Flashback…While working at convenience store, Cha Ji Won studies to become a police officer. Baek Hee Sung is a customer. While checking his ID for beer she notes he looks young for his age. She says she hasn't seen him around. Hee Sung says this area looks like a nice place to start over.
While Ji Won sleeps, Hee Sung practices to videos on how to smile naturally. He cooks. When Ji Won startles him he forces a practiced smile. She praises his soup. She gets their daughter Baek Eun Ha (Jung Seo Yeon) ready for school. Eun Ha says daddy does her hair better. Eun Ha brings the hair dryer to Hee Sung and asks him to do her hair. He asks where her mother is. Eun Ha shares that mom went to clean his workshop. That wipes the smile from his face.
Ji Won enters Hee Sung's shop.
Reporter Kim wakes trussed and gagged on the floor under the shop.
Ji Won finds the pieces of a broken tea cup. Hee Sung arrives and tells her he was clumsy yesterday when he served tea. She asks who came for tea. Hee Sung says it was a friend from middle school. Ji Won is surprised and pleased. Hee Sung leads her out of the shop. She smiles at him. He returns his practiced smile.
Reporter Kim struggles to free himself.
Crime of the episode…
A social worker arrives at her employer's home, surprised to find the door unlocked. She's even more surprised to find her employer dead in a pool of blood.
While forensics gather evidence, Detective Choi Jae Sub (Choi Young Joon), Ji Won, and Officer Im Ho Joon (Kim Jin Woo) arrive. They observe the body. Officer Im points out the missing thumbnail is like the serial murders in Yeonju. Officer Im tells Detective Choi that the culprit committed suicide so the cases were closed. The distraught son arrives.
Hee Sung closes his shop for the day. He unlocks the door to the basement. He sits in front of Reporter Kim and removes his gag. Reporter Kim asks why he's doing this. He says this is a crime. Hee Sung says 18 years ago they were opposite positions.
Flashback…Hee Sung is bound by his school mates to a tree. A young Moo Jin slaps Hee Sung when he says he should have twisted his neck instead of hurting his finger. Hee Sung says this is his once chance to beat him. Moo Jin believes Hee Sung saw his father commit murder. Moo Jin asked if Hee Sung helped his father do it. Hee Sung says Moo Jin is afraid of him. Moo Jin comments and then he and his two friends throw rocks. Hee Sung promises he'll pay him back.
Did Hee Sung removed Moo Jin's nail?
Hee Sung says it is payback time. Hee Sung picks up a hammer and places it on Moo Jin's face. He repeats the words Moo Jin said to him before throwing the rocks. Moo Jin says they were young and it wasn't the man he's evolved to me. Hee Sung chuckles he's just joking. Moo Jin asks if he wants money. Moo Jin admits he's scared. Hee Sung says he's just like his father. He never feels anything for anyone. He takes out Hee Sung's cell phone and requests the passcode.
At the autopsy they learn the victim was stabbed multiple times. The culprit broke her ankle and thumbnail after she was dead. The coroner remembers the serial murders in Yeonju had similar traits. She recalls the culprit's name was Do Min Seok. Coroner notices something else about the victim's hand.
At the police station, the team gathers to discuss the case. Officer Im says it is similar to the serial murders in Yeonju. Detective Choi counters the murderer is a copycat. They discuss details. The victim was a money lender and rich. She was a major donor to the welfare center.
Flashback…the social worker that found the body tells Detective Choi that the welfare center took care of the elderly victim.
Flashback…the son searches for his mother's ledger and can't find it.
Ji Won notes Do Min Seok wasn't a media darling like other serial killers. She doesn't understand why Do Min Seok is being mimicked. Officer Im believes Reporter Kim's articles about the murders revived interest.
With Hee Sung watching, Reporter Kim calls in sick. He promises his boss he'll be back tomorrow. When he tries to explain his situation, Hee Sung ends the phone call. Hee Sung notes he's got 3 days before someone reports Reporter Kim missing. Reporter Kim asks if they are in the basement of Baek Hee Sung's shop. Recall Reporter Kim does NOT know Do Hyun Soo is Baek Hee Sung. Reporter Kim assumes Hyun Soo is Hee Sung's employee. Hee Sung confirms this. Reporter Kim shares that Hee Sung's wife gave him the address and she's a detective for the violent crimes group. Reporter Kim says he'll be caught in no time. Hee Sung sits down and tells Reporter Kim he's missing how he escaped capture. Reporter Kim finally realizes Do Hyun Soo is Baek Hee Sung and married to JW. Reporter Kim says he lied to him yesterday. Hee Sung offers the truth though it will cost him. Reporter Kim doesn't want to know. Hee Sung taunts then admits he killed the foreman.
Flashback…Do Hyun So views the dead foreman's body. His classmate Hae Su tell him this isn't right. He begs to differ. He feels great. He smiles.
Hee Sung leaves Reporter Kim to ponder the reveal.
Ji Won and Officer Im work the case. Officer Im finds Reporter Kim's last article on Do Min Seok, it highlights broken ankles and missing nails. Officer Im points out this killer used a noose like the serial killer. But it isn't an exact match to the dog leash the Yeonju serial killer used. Ji Won gets a call from the principal who asks her to come to the school ASAP.
Hee Sung locks the door to the basement. He turns Reporter Kim's phone off and puts the bag with it behind clothes in his closet. He gets upstairs and sees 2 missed calls from his daughter's school.
The victim's son demands the social worker tell him where his mother's ledger is. He's desperate for cash. She doesn't know where it is. She tries to walk away but he grabs her. Detective Choi approaches and stops him. Detective Choi learns the son has gambling issues. The social worker asks if the murderer was a serial killer. Detective Choi says it was a copycat. The social worker shares the victim called her last night with questions about her will and how to get it notarized.
Ji Won tells the little girl that hit Eun Ha to apologize and the girls can make up. The mother of the little girl doesn't agree. Eun Ha touched her daughter's doll without permission. Ji Won counters that the girls need to learn how to reconcile without adults mucking it up. The mother calls Eun Ha a thief and chides Ji Won to teach her daughter better. Ji Won is appalled. Hee Sung arrives. He claims this is his fault for not educating his daughter properly. The mother is taken aback. Ji Won is taken aback. Eun Ha is taken aback. As directed Eun Ha apologizes. She sobs. Ji Won isn't happy.
Outside Ji Won points out that her husband ignored his daughter's feelings on the matter. Ji Won points out touching a doll doesn't merit a punch. He's disappointed their daughter who considers him her biggest ally. Hee Sung reads her body and asks if he's made a mistake. He promises to defer to her next time and make it up to Eun Ha.
The coroner calls Ji Won to report lipstick was on the thumb of the victim. Ji Won says the victim wasn't wearing lipstick.
Eun Ha points out that her father took her opponents side. He says he saved her reputation. Now people won't doubt her but will doubt her opponent. Eun Ha declares she had to apologize. Hee Sung counters that her opponent was crying because she lost her doll.
Flashback…Hee Sung dumps the doll in the trash can.
Hee Sung cajoles his daughter to eat and smile. Eun Ha declares he's her favorite.
Detective Choi interrogates the son. He shows him the will donating all the money to the welfare center. The son gets upset. He declares the social worker did this. Detective Choi says he heard the son had an argument with his mother. The son asks if he has proof. Detective Choi asks when the son left his mother's house last night. The son refuses to answer unless a warrant is produced.
Detective Choi shows Ji Won the will. Ji Won counters the lipstick on the thumbnail is the murderer's and that isn't the victim's son. Detective Choi yells the will is everything. They demand Officer Im pick what is important. Officer Im dodges and says he'll have to think about it. Detective Choi declares the murderer is the son. Ji Won thinks it is a woman who has the lipstick. Ji Won stares at the will. She realizes the fingerprint was made with lipstick.
Isn't the social worker the obvious choice?
Forensics takes a sample from the will. Ji Won demonstrates and details what she believed happened to Detective Choi and Team Lead Lee Woo Cheol (Choi Dae Hoon). Detective Choi declares the social worker is the obvious choice. Team Lead Lee wants to know why the social worker would kill. Forensics call and confirms the thumbprint on the will was made by lipstick.
Hee Sung pulls items out of Reporter Kim's bag. He looks at the necklace. He talks to Ji Won's mother Moon Young Ok (Jo Kyung Sook) and thanks her to watching Eun Ha. Ji Won's mother says since he is taking care of her daughter, she'll take care of his. When Hee Sung hangs up he studies the necklace then starts to page through Reporter Kim's notebook. He sees the annotation about the meeting with Mr. Nam.
Hee Sung offers Reporter Kim water if he tells him about the meeting with Mr. Nam. Reporter Kim says it is nothing. Hee Sung pours some water on the floor. Reporter Kim says Mr. Nam had a tip. Hee Sung gives Reporter Kim a drink for the tip. Reporter Kim says he wrote an article about Hee Sung's father and him. Reporter Kim says the meeting with Mr. Nam is today and he shouldn't miss it.
Ji Won introduces herself to the social worker. She explains the DNA on the will is the murderers. She wants the social worker to provide a DNA sample. The social worker refuses. She says Ji Won can't prove she killed the woman.
Detective Choi reviews CCTV of the social worker. She's holding a bag that might have physical evidence. They believe she might be the killer.
Mr. Nam waits for Reporter Kim. Hee Sung calls him via Reporter Kim's phone. He says he's too busy to meet and asks for the tip. Nr. Nam gets out a flyer about the killer and says the killer left town in the summer of 2002 and he lived with him in the fall of 2002 to summer of 2005. Mr. Nam never imagined that his roommate was Do Min Seok's son. He shares that Do Hyun Soo didn't have normal emotional reactions. Reporter Kim asks for more. Mr. Nam says Hun Su is threatening him. That gets Hee Sung attention.
Detective Choi believes the social worker didn't leave the physical evidence in her home.
Flashback…He recalls the social worker looked to the roof of her apartment when she spoke to him.
Detective Choi goes to the apartment rooftop.
Flashback…The social worker takes the bag with the physical evidence and throws it in a cubby.
Detective Choi opens the cubby and finds the bag. He calls Ji Won and reports he found the physical evidence. We see the lipstick stained nail. Ji Won hangs up and arrests the social worker. She asks to freshen her makeup because her appearance today may affect the sentence she receives. Ji Won allows her to primp. She puts on the lipstick. The social worker says she killed the woman because she was tired of the number of stairs she had to climb to visit the victim.
Flashback…The victim signs the will and asks the social worker to get it notarized. The victim says all she'll need is a visit from the social worker every day. She turns and asks for a back rub. The social worker grips the knife she's cutting the apple with and kills. She calls the police to report finding the body.
The social worker tells Ji Won not to judge her. She says 3% of people in the world are like her. She spies a brow razor in her makeup bag. She looks at Ji Won and says someone close to her could be just like her.
Mr. Nam tells Hee Sung he got a call from someone that he thought was Do Hyun Soo. That person told him that he'd waited for him to become happy. Mr. Nam admits that he wronged Do Hyun Soo in the past.
Flashback…Mr. Nam stabs Do Hyun Soo on a rainy night in the woods. They struggle. Mr. Nam yells he needs money and wants Do Hyun Soo's money.
Hee Sung tells Mr. Nam the call was from someone else, Do Hyun Soo is dead. Mr. Nam is pleased to hear it. Hee Sung doesn't like that. He tells Mr. Nam some people deserve to die.
The social worker cuts Ji Won's face below her eye. She smiles and says she's ready to be arrested now. Ji Won slaps the social worker repeatedly. Then she picks up the brow razor. The social worker yelps in surprise.
Officer Im stops the police from entering the women's restroom and states Detective Cha has it well in hand.
The social worker declares Detective Cha can't assault her. Ji Won asks if hurting those weaker than her makes her feel superior. She holds the brow razor against the arteries in the social worker's neck and tells her the time to bleed out from a cut. The social worker pleads with her not to kill her. Ji Won smiles and says she was just joking. She puts handcuffs on the social worker and tells her she has the right to a lawyer.
That was interesting.
Gong Mi Ja (Nam Gi Ae) (Hee Sung's Mother) is surprised when Hee Sung stops by the pharmacy where she works. He claims he missed her to the customer she is helping. When the customer leaves his mother reveals that customer is on antidepressants. She likes that others aren't really happy underneath the veneer, just like her. She asks what he wants. Hee Sung asks for sleeping pills.
Hee Sung waits outside the police station for Ji Won. She dashes into the shelter of his umbrella. He notices the bandage on her face. She lies that she cut herself. She declares the rain is romantic. They start to walk together. They agree to get pancakes.
A man in a raincoat with a hood comes into a hardware store. He thumbs the dog leashes. He picks one for purchase.
Sitting in his eatery alone, Mr. Nam reads the article by Reporter Kim which ends with the question – where did Do Min Seok's son flee to? Nr. Nam calls Reporter Kim. He starts to leave a voicemail.
The man in the raincoat approaches the eatery.
In the voicemail, Mr. Nam says he recently heard that Do Min Seok's son, Do Hyun Soo, helped his father commit the murders.
The man in the raincoat stands outside the eatery.
Mr. Nam hears the door open. He stands and knows that man in the raincoat is Do Hyun Soo. He yells into the phone that Do Hyun Soo has come for his revenge. The man in the raincoat pulls out a knife and approaches Mr. Nam. He's not fast enough to poise the scissors he grabs. The man in the raincoat stabs Mr. Nam.
The man in the raincoat enters a room. There's a wall of articles about the murders. He takes Reporter Kim's article and stabs it into the wall with the knife he just used on Mr. Nam.
Ji Won wakes in bed. The clock reads 3:30am. The front door opens and a man in a raincoat enters the apartment. He pulls back the hood and reveals his face. Hee Sung and Ji Won stare at each other as the lighting flashes outside.