Armed with the information that Shin Da Hye is alive, cold case team profiler Park Hae Young (Lee Je Hoon) points out that the only person who can explain what happened to her is Da Hye herself. Team leader, Cha Soo Hyun sets the team of Da Hye’s trail. Detective Kim Gye Chul (Kim Won Hae) follows checks into Da Hye’s family, while Soo Hyun goes to interview Da Hye’s fiancé, Min Sung to find out more about her. Min Sung hands over a box of tapes of Da Hye’s voice, recorded while she practiced her acting.
Hae Young, meanwhile, interviews the shady manager of Da Hye’s former agency, who turns out to have a laundry list of criminal charges against him. After some threatening, the manager relates how he supplied women, including Da Hye, to Han Se Kyu’s parties, and adds that Se Kyu liked the fact that she was a good girl. On one occasion, Se Kyu sexually assaulted Da Hye, while one of his friends surreptitiously filmed it. Later, the manager was present when one of Se Kyu’s friends threatened to give the tape of Se Kyu partying with drugs to the police, if Se Kyu didn’t stop his father from prosecuting his own father over a bribery scandal. Se Kyu retaliated by robbing his friends’ houses to find the tape, and took the valuables to make it look like a normal break-in.
Hae Young gives Soo Hyun a confused report about Se Kyu and the necklace as he leaves. When she asks Min Sung about the necklace, he doesn’t know anything, but points out that detective Lee Jae Han (Jo Jin Woong) had asked him the same thing, twenty years ago. Unable to help, Jae Han had turned to Da Hye’s friend, Ji Hee. Min Sung passes on Ji Hee’s contact information to Soo Hyun, but adds that he hasn’t seen her since before Da Hye’s funeral. Soo Hyun speculates that she may have been unable to go.
Soo Hyun calls cold case team member, Hun Ki (Lee Yoo Joon), who confirms that Ji Hee has no remaining family, and that she left Korea for Germany in 1995. He also confirms that Ji Hee returned to Korea two weeks earlier. When Soo Hyun goes to check out the hotel room Ji Hee stayed in when she arrived, she notices that the hotel is very close to the hospital where Da Hye’s mother is getting a liver transplant.
She immediately goes to the hospital, where Gye Chul leads her to the room of the organ donor for Da Hye’s mother. Outside the door, they run into Da Hye’s sister, and when they enter the room, Soo Hyun’s suspicions are confirmed: The donor is Da Hye, who returned to Korea as Ji Hee to donate her liver to her mother.
With some coaxing, Da Hye tells the story of what happened twenty years ago, after Se Kyu got back the video of him assaulting her. He promised to return it to her, but first made her watch it, then showed off his haul of jewellery and money. Finally, when he passed out, Da Hye stole the blue diamond necklace. Later, when Se Kyu was released from prison, he demanded she return the necklace, but Da Hye refused, intending to turn herself into the police the next day. That night, Se Kyu came to her home, and murdered Ji Hee, as Da Hye watched from a hiding place. Da Hye ran away to her mother’s house, and when her family got the call that Da Hye was dead, Da Hye decided to live her life as Ji Hee. When Soo Hyun points out that without evidence, her story would be hard to believe, Da Hye’s sister says that she has the evidence.
Meanwhile, Hae Young tracks down Se Kyu at a hostess bar. When Hae Young starts talking about Da Hye, Se Kyu clears the room, and listens nervously as Hae Young recounts all the details of the case that point to Se Kyu’s guilt. The tables are turned, however, when Se Kyu readily admits to killing Da Hye, pointing out that Hae Young can’t do anything about it. The two men face off, but Hae Young ends the conversation by telling Se Kyu that he’ll get him no matter what, and leaves the room.
Back at the office, a nervous Gye Chul starts berating Hae Young for confronting Se Kyu, but they’re interrupted by the arrival of their supervisor, Ahn Chi Soo (Jung Hae Kyun). Expecting a tirade, the entire team is taken aback when Chi Soo merely asks what reason Hae Young had for his actions. Soo Hyun explains that she ordered the investigation, and asks to interview Se Kyu. When Chi Soo asks what evidence they have, Soo Hyun produces a tape recording of the night in question, accidentally recorded when Da Hye left her tape running, and later found by her sister when she cleared out the apartment.
As Chi Soo and the team listen to the recording, Da Hye narrates that that night, Ji Hee had stayed over, and Da Hye fell asleep while practicing her lines. Da Hye had woken up thirsty, and just as she went to the kitchen, Se Kyu burst in and attacked the sleeping Ji Hee, telling her that he was punishing her for stealing from him. Da Hye, meanwhile, hid behind the refrigerator.
At a fancy restaurant, Chi Soo plays the same recording for Se Kyu and police superintendent, Kim Bum Joo (Jang Hyun Sung). Bum Joo reassures Se Kyu that he’ll take care of the whole thing, but Se Kyu is more angry than reassured. When Bum Joo tells Se Kyu not to attend the interview, Se Kyu refuses, saying that he has to go to crush Hae Young. Meanwhile, he directs Bum Joo to take care of the witness.
Back at the police station, Gye Chul is skeptical as Hae Young predicts that Se Kyu won’t be able to resist coming in for an interview, and he’s proven right when Se Kyu shows up. Soo Hyun, meanwhile, is on her way to pick up Da Hye from the hospital.
As Hae Young reads Se Kyu his rights in the interview room, Bum Joo and Chi Soo watch from the observation room. Hae Young starts out by informing Se Kyu that a witness to Da Hye’s murder. Se Kyu coolly listens as Hae Young plays the recording, and then confirms that it’s his voice speaking on it, but denies that he killed Da Hye. Se Kyu dares Hae Young to come up with any evidence placing that recording in Da Hye’s apartment twenty years ago.
Meanwhile, Soo Hyun arrives at the hospital to find Da Hye has already left with a male nurse. Quickly realizing that something’s up, Soo Hyun runs to the security office, and finds Da Hye via the CCTVs, in the parking garage. Soo Hyun runs the stairs, and bursts into the parking garage, just in time for the male nurse to attack her from behind.
Back in the interrogation, Hae Young bursts the arrogant Se Kyu’s bubble by playing him the rest of the recording. That night, in Da Hye’s apartment, when Se Kyu finished strangling Ji Hee, Se Kyu turned the apartment upside down as the terrified Da Hye cowered behind the fridge. Finally, unable to hold it in any longer, Da Hye let out a gasp that alerted Se Kyu to her presence. But, before he could find her, Se Kyu was distracted by Min Sung knocking on the door and calling out Da Hye’s name. Da Hye was forgotten as Se Kyu hurriedly stuffed Ji Hee’s body into a bag and left.
Back in the interrogation room, Hae Young adds that Min Sung had already given a statement confirming that he came by the apartment that night. Se Kyu is shocked at this new evidence, since it didn’t match the recording he’d heard, and Hae Young pointedly looks at Bum Joo and Chi Soo in the interrogation room, as he wonders how the evidence could have landed in Se Kyu’s hands in the first place.
Disasters pile up on Se Kyu, as their surprise witness is brought in by a bruised Soo Hyun: Da Hye, herself. We flash back to the hospital parking lot, where Soo Hyun fought with her attacker, then ran for the car that he had already stashed Da Hye in, and drove it away. Back in the interrogation room, a terrified Se Kyu spills everything. As Hae Young points out that he’s just confessed, Se Kyu attacks Hae Young, then starts throwing furniture. It takes Hun Ki and Soo Hyun to restrain him, and then arrest him. Hun Ki leads him away as Soo Hyun comforts the shaken Da Hye.
As Soo Hyun and Hae Young wheel Da Hye out to the hallway, they run into the waiting Min Sung. At first, Da Hye can’t even look at him, but soon they’re crying in each others’ arms. Their touching reunion has Soo Hyun tearing up, as she thinks back to Jae Han’s last words to her.
The next day, back at the hospital, Hae Young asks Da Hye why Se Kyu was so determined to get the necklace back. She tells him about the floppy disk in the necklace case, and goes on to explain that she gave it to Jae Han, twenty years ago. In 1995, Jae Han persistently tries to get in touch with Ji Hee, to the point of going to her house, and asking her neighbours about her. Da Hye had gone to Ji Hee’s apartment to get her passport, and sees Jae Han trying to track down the floppy disk. Da Hye mails Jae Han the disk to get him off her back.
In the police station in 1995, Bum Joo openly flips through Jae Han’s mail and picks up Da Hye’s package. When Jae Han comes back, he’s met by Bum Joo with detectives from the prosecutor’s office, who want to know more about the disk. It’s not until the next day that Jae Han confronts Bum Joo, with the knowledge that Bum Joo had erased most of the information on the disk implicating the larger corporations and the politicians, and left only Sekang Construction as the patsy for the bribery scandal. Bum Joo in unapologetic, and tells him to leave if he doesn’t like it. Instead, Jae Han promises to stay and take him down in the end.
In 2015, Bum Joo takes out his frustrations by beating up Chi Soo, but a glimmer of rebellion appears when Chi Soo doesn’t pass on the information of Hae Young finding Jae Han’s radio. Instead, Bum Joo reminds Chi Soo that he will be the one in trouble if the truth of Jae Han’s death is revealed.
Meanwhile, the cold case squad is celebrating with food and drink, as Gye Chul reenacts the confession scene, annoyed that he missed it. When Soo Hyun makes to leave to finish up the paperwork, Hae Young forestalls her and goes back to the office himself to do it, telling her to put ointment on her bruised face. Back at the office, Hae Young has the ointment ready, but puts it back in his drawer and gets down to work. But, it’s not long before he starts hearing Jae Han calling him on the radio. Hae Young has no idea where the radio is, but starts moving towards the sound.
A dispirited Chi Soo walks up the stairwell to the office and pauses on the landing. As he looks at his battered face in the window, he thinks back to Jae Han’s last moments (in 2000), when Jae Han sat wounded in the woods with someone chasing him. As the mysterious person shoots Jae Han, we finally see that it’s Chi Soo who did it.
Back in the present, Hae Young walks towards the sound of the radio, and finds it in a desk drawer. As he pulls it out, Chi Soo walks in to the office and says his name. As the two men look at each other, the episode ends.
Before we get into it, let me add a fun fact. I just realized that Lee Dong Ha, the actor playing Han Se Kyu, is also playing Mi Mo’s awful ex-boyfriend in “One More Happy Ending”. He’s pretty good at playing terrible people, so here’s hoping he’s a super nice guy in real life.
Anyway, back to “Signal”. So much happened this episode that my comments are going to be all over the place. Let’s start with Soo Hyun. I don’t know if I’ve mentioned this before, but Soo Hyun is a fantastic character; brave, intelligent, loyal, but also clearly can’t resist hamming it up a bit when she makes the big reveal. Also, that fight this episode was amazing, because when it became clear that there was no way to beat the guy, she figured out how to get out of the situation instead. Awesome.
This episode also sealed what a loathsome character Bum Joo is, between his blatant opportunism, and his habit of deflecting investigations from his rich masters. I was pretty excited when Jae Han told him off, but only until I remembered how Jae Han ended up as a result.
My final thought is, of course, the cliffhanger. Finding out that Chi Soo killed Jae Han moments before he walked in on Hae Young holding the radio had me on the edge of my seat. Here’s hoping Hae Young can come up with a convincing explanation before next week’s episode. Or, maybe Chi Soo will switch sides?