Police profiler Park Hae Young (Lee Je Hoon) finds section chief Ahn Chi Soo (Jung Hae Kyun) in a stand of trees next to the parking lot of Injoo Hospital, bleeding from his stomach. When Hae Young tries to call for help, Chi Soo stops him, then tells him about how he heard the voice of police detective Lee Jae Han (Jo Jin Woong) coming from the radio. Chi Soo knows that this isn’t possible, since Jae Han is dead by Chi Soo’s hand. Hae Young, but Chi Soo cryptically adds that he checked on the thing under the stairs after he heard the radio. Hae Young can do nothing as Chi Soo cries his regret for killing Jae Han and dies.
Hae Young is unresponsive in the hospital corridor as two detectives question what he was doing with Chi Soo. Hae Young’s entire precinct comes running, including the members of the cold case squad, demanding to know what happened. The situation starts to get heated as the cold case squad tries to defend Hae Young against the other officers, but when chief, Kim Bum Joo (Jang Hyun Sung) walks in, silence reigns. When he demands to know where Chi Soo is, Hae Young tells everyone that he’s dead.
Back at the station, in the meeting room, Bum Joo questions Hae Young in front of the entire precinct, demanding to know how and why they were meeting there. Hae Young tells them that it was about the Injoo rape case, that Chi Soo revealed that it was fixed from the start, but that he wasn’t able to get any more details from Chi Soo before he died. An angry Bum Joo assigns the detectives to investigate his death, but excludes the cold case squad, since Hae Young is their number one suspect.
In interrogation, Hae Young can’t explain the circumstances of either his meeting with Chi Soo or the argument they had in the squad room in episode 9. When pressed, all Hae Young can do is repeat that it wasn’t him. Meanwhile, the other detectives discover that Chi Soo had a daughter who had recently passed away from cancer. They also discover that one of the last calls he made was to gangster, Kim Sung Bum, who admits under interrogation that Hae Young had been asking him about Chi Soo, and he didn’t want to get into a fight between detectives. When the detective in charge reports this to Bum Joo, he tells him to thoroughly investigate Hae Young.
Cold case team leader, Cha Soo Hyun (Kim Hye Soo) tries to find out more about the investigation, but is rebuffed by the detective in charge. She asks him if they found a radio with a smiley-face sticker (Jae Han’s radio) on it in Chi Soo’s possession, but he tells her to get lost.
When a shell-shocked Hae Young is released from his interrogation, Soo Hyun takes him up to the roof where they talk. Soo Hyun doesn’t believe that Hae Young killed Chi Soo, and Hae Young takes that small hope and tells her (almost) everything. He tells her that Chi Soo, along with Sung Bum, set up the bribery case of Detective Lee Jae Han (Jo Jin Woong), and that in the end, Chi Soo killed Jae Han. Soo Hyun is distraught as she demands to know why, and Hae Young explains that it all went back to the case in Injoo.
Back in 1999, Jae Han asks the high school teacher of rape survivor, Kang Hae Seung, about whether she was dating any members of the student council board. The teacher is incredulous at the idea, but sobers up when Jae Han asks to see the students’ files. The Bum Joo of 1999 hears about Jae Han’s interference in the case and rages at the chief of the Injoo police station for not figuring out who wrote the initial note that started the controversy. Bum Joo instructs the chief to remove the seven members of the council from Injoo.
Meanwhile, as Jae Han goes through the student files, he narrows in on one student, Lee Dong Jin, who is somewhat introverted and sensitive. He goes to the hospital to see if any of the students had hung around Hae Seung’s room.
Back at the police station, the chief is frantic as he calls up the student council members’ families and tells them to send their kids away. One kid isn’t answering, and he sends Chi Soo to get the kid out. On his way, Chi Soo passes Jae Han asking for directions.
Chi Soo pushes the reluctant Dong Jin out of his house and into the car, but before he can drive away, Jae Han pops up in front of them like the Terminator. Jae Han gets into the back seat with Dong Jin, and congratulates Chi Soo on finding him, too. He instructs Chi Soo to drive to the station, so that they can talk to Dong Jin about what he wrote in the note.
Back at the station, the cops are shocked to see Jae Han with Dong Jin (is everyone in on the cover-up?), as they walk to the interrogation room. As Jae Han sits down with Dong Jin, Bum Joo issues orders for them to call Dong Jin’s parents. In the interrogation room, Jae Han coaxes Dong Jin to tell him about what happened. He asks about the “one” person mentioned in the note, but Dong Jin pretends not to know anything. It’s not until Jae Han asks about his relationship with Hae Seung that he cracks, and the story starts to spill out.
One day, Dong Jin was approached by Park Sun Woo (Hwang Chan Hee), Hae Young’s older brother, to use Dong Jin’s house to tutor Hae Seung. Dong Jin is surprised by the two of them together, and asks if Sun Woo has a thing for Hae Seung. Sun Woo denies it, and indeed, they do nothing but homework.
Before Dong Jin can continue with his story, his irate father appears and drags him away, over Jae Han’s protests. In the end, Jae Han can do nothing but let them go, since Dong Jin is a minor. Bum Joo instructs Jae Han to get a witness summons, and get all seven council members to come in and give a statement. But, once he’s out of Jae Han’s earshot, he tells the Injoo chief that they need to designate a fall guy with no money or power to take the place of the “one” person who started it all. And, the only person mentioned in the statement was Sun Woo.
Back in the present, Hae Young hands a cup of tea to Soo Hyun in his one-room apartment. As she looks around, Soo Hyun notices that the place is stuffed with books and case files, all maintained in meticulous order (is this why Hae Young was so sympathetic to Jin Woo?). Hae Young hands Soo Hyun the only information he’s managed to find on the Injoo rape case, in the poorly maintained case files.
Before Soo Hyun can look at what he’s collected, she asks to hear the story of what happened to him and his brother in Injoo. We flash back to 1999 with Sun Woo correcting Hae Young’s homework. When it turns out to be correct, Hae Young demands that Sun Woo make good on his promise to give him a wish, and then wishes that the family would go out to eat together for omurice. There’s a knock at the door, and instead of their mother, it turns out to be Jae Han’s partner, Jung Jae and another policeman. The two men take Sun Woo away, with a crying Hae Young following behind.
Hae Young goes home when Sun Woo tells him to, but when Sun Woo doesn’t return, he goes to the police station to find him. Instead, he finds an out-of-patience beat cop who throws him out. Back at home, Hae Young’s father leaves his mother and drags Hae Young along, refusing to believe that Sun Woo is innocent.
When Sun Woo is released from detention, Hae Young returns to see him, and instead finds him dead, having slashed his wrists open. In fact, Hae Young had no idea why any of this had happened, until an old classmate ran into him at him as a teenager, at his part-time job at a convenience store (shades of Jin Woo again). The classmate mentions a rumour about one of the town bad boys lying to the police about Sun Woo and Hae Seung riding the bus together.
Hae Young goes to confront the guy who said it, but it devolves almost immediately into an argument. When Hae Young demands that he goes to the cops, and retracts his lies, the guy tells him that it was the police who told him to lie in the first place. Hae Young is shocked, but he persists and ends up in a fight with the guy and his friends. When they finally beat him, Hae Young’s persistence is rewarded by the guy reminding him that like his brother, he has no money or power.
In the present, Soo Hyun tells Hae Young who was on the task force that went from Seoul, but when Hae Young asks to speak with them, she refuses, telling him that he can’t bring more suspicion to himself.
Back in 1999, Jae Han interviews the seven members of the student council and they all point at Sun Woo as the one who made them do it. Jae Han is skeptical, and the feeling increases when he finally gets to interview Sun Woo. Sun Woo has no evidence to back up his claim of innocence, except for the fact that he was the one who gave the student council photo to Jae Han in the first place. Jae Han looks convinced, but has no evidence to back it up. He goes to see Dong Jin again, but is turned away at the door by Dong Jin’s father. As he goes to leave, Jae Han notices the huge willow tree in their yard, and thinks back to the note that Dong Jin posted on the school website, that stated that everything started at the willow tree house.
Jae Han checks out the abandoned restaurant that Jung Jae found to be the crime scene. On his way out, he spots a roadside vendor and asks him if he ever saw kids hanging around the place. The vendor has not only never seen kids hanging around there, but also tells Jae Han that the restaurant was called Willow Tree Cave, not House. Jae Han’s next stop is the farming couple who testified that the restaurant was called Willow Tree House. He accuses them of being greedy and lying to protect their son, who works for Injoo Cement, but in fact, the detective from Seoul, i.e. Jung Jae, had coached them in what to say.
Back at the station, Jae Han takes Jung Jae outside and confronts him. He’s obviously not ready to accused him of taking money from Bum Joo in exchange for helping to fix the case, but Jung Jae confesses. Jae Han is enraged that he would set up an innocent kid just for money, but Jung Jae has a wife and two kids and can’t support them on his salary. Jung Jae had been on point of ending up on the street when Bum Joo had offered him the money. He begs Jae Han to look the other way, just this once.
Jae Han confronts Bum Joo, and asks if he got money from Injoo Cement, the only big company in the area. Instead of answering, Bum Joo takes him to the observation area for the interrogation room, and shows him Chi Soo interviewing Hae Seung. Chi Soo asks if Sun Woo was the instigator of the incident, but before she can answer, Jae Han bursts in to the interrogation room, and begs her to reconsider. Instead, Hae Seung bursts into tears and says that it was Sun Woo.
Later, Jae Han asks Bum Joo if this whole case was about money, and Bum Joo points out that everyone needs money, and that with her life now in tatters, even Hae Seung needs money. Jae Han asks the identity of the “one” person, whether he was important enough for the whole city of Injoo to cover for him, but Bum Joo repeats that it was Sun Woo.
In the present, Soo Hyun goes to see Jung Jae, who is now running a convenience store. When she asks about the Injoo case, though, he pretends not to remember it. He’s taken aback when Soo Hyun adds that Chi Soo was murdered, and gets up to leave. Soo Hyun stops him, and tells him what Chi Soo said before he died, that he had killed Jae Han himself. Jung Jae is shaken, but still says nothing. As he goes to the door, Soo Hyun reminds him that Jae Han was his best friend. Finally, Jung Jae says that Jae Han never gave up on the Injoo case, and leaves.
The next day, Hae Young parks his car at the station, only to notice Sung Bum’s car pulling out behind him. As he looks, he spots an unusual accessory hanging off Sung Bum’s rearview mirror, and clues in that he saw that car driving past him on the way to Injoo Hospital. Hae Young figures out that Sung Bum was there the night Chi Soo died.
That night, Soo Hyun picks him up at the station, and the two of them drive to a house in the name of Sung Bum’s mother. On the way, Hae Young explains that Chi Soo’s stabbing looked like the work of a professional. Hae Young profiles Sung Bum, describing him as someone who wouldn’t trust others, and would keep evidence somewhere as insurance, but not in his home or office. When they arrive, Soo Hyun easily breaks into the house, with a reluctant Hae Young following behind.
The house is covered in dust and offers up no clues as to what Sung Bum is hiding. They’re about to leave when Hae Young notices an elaborate staircase outside, and recalls Chi Soo’s last words, that he checked on the thing under the stairs after discovering that Jae Han was alive. They call Gye Chul to check Chi Soo’s whereabouts in the days leading to his death, and discover that he went through the same tollbooth that they used to get there.
Hae Young grabs a shovel and starts digging, with Soo Hyun shining her flashlight. When he finally hits something, he starts moving dirt aside with his hands, and it’s not long before he uncovers bones. As Soo Hyun realizes what they’ve found, she starts to help him, and uncovers a shoulder with a metal in it (I have no idea what this bone is called, sorry). She reaches out to the police ID next to the body, and with shaking fingers, pulls out the card from the holder to see Jae Han’s face.
Come on, “Signal”! How am I supposed to wait a week to find out what happens next? And the preview at the end only made it worse. Actually, the worst thing about having to wait is that I have no idea why Sun Woo was framed. Obviously whoever was guilty of being the “one” was important enough to cover up, but really, who is it? And why is the whole town willing to lie about it?
Back to the story at hand, let’s talk about everyone’s least favourite character, Bum Joo. He has to be one of the most loathsome characters I’ve seen in a drama, but the really evil thing about him is the effect he has on people. I’m sure Chi Soo imagined that he would only have to do this one thing for Bum Joo (and for the good of Injoo or whatever the reason was), and then he could go back to his normal life. Instead, Chi Soo ended up on a downward slope of criminality, broken only by frequent abuse from a man he knew to be a monster. And 17 years later, he ends up stabbed to death in a parking lot, used as a pawn in Bum Joo’s evil schemes.
You can see it in the course of this episode, on the face of the Injoo chief of police, as Bum Joo keeps upping the ante on his demands, eventually by framing the innocent Sun Woo.
Now that I’ve grossed myself out by talking about Bum Joo, let’s go back to our heroes. I’m glad we got to see some of Hae Young’s past, though I’d love to know how he got from the floor of that pool hall to the police force. I also wonder how, if Sun Woo had survived, Hae Young’s life would have turned out. Would he still be a cop? Maybe we’ll get to find out.