Signal Episode 09 Recap: Hongwon-dong Opens Soo-hyun's Old Wound
Signal, Season 1, Episode 09 tvN · Written by Kim Eun-hee · 2016
A missing detective, a buried serial case, and Soo-hyun’s private nightmare all meet on the same mountain trail.
Park Hae-young (Lee Je-hoon) has been treating the walkie-talkie like a miracle and a burden. In Episode 09, it becomes evidence.
That shift matters. The radio is no longer only the impossible object that lets Hae-young speak to Lee Jae-han (Cho Jin-woong) across time. It is also the thing found near Jae-han’s abandoned vehicle 15 years ago, tagged by crime scene investigators, nearly thrown out of storage, then kept by Cha Soo-hyun (Kim Hye-soo).
The case of the week is the Hongwon-dong murders, but Episode 09 is doing two investigations at once. One asks who killed women in 1997, changed his disposal method, and kept killing for years. The other asks why every road around Jae-han’s disappearance keeps leading back to powerful cops, old favors, and the Inju case Hae-young has spent his life trying not to touch.
Neither question stays abstract for long.
Soo-hyun takes back Jae-han’s radio from Hae-young
Soo-hyun finds the walkie-talkie in Hae-young’s possession and immediately knows what it is. Jae-han carried it like a good luck charm. After he disappeared, it was found on the mountain where his vehicle was left. For years it sat in evidence storage, then Soo-hyun rescued it before disposal.
Hae-young cannot explain why he has it. Not honestly. Not yet.
So the conversation turns into a mutual interrogation. Soo-hyun wants his connection to Jae-han. Hae-young wants to know why she is so guarded about the disappearance. When he asks whether there are secrets he must never learn, she denies it. Then she takes the radio back.
Both of them are telling partial truths. Soo-hyun does not know about the transmissions, but she knows the radio belonged to a man she has spent 15 years searching for. Hae-young does know about the transmissions, but he still has no clear answer: why him, and why 11:23 p.m.?
Once the radio is out of his hands, Hae-young starts reading Jae-han’s disappearance like a cold case. Jae-han was framed as a corrupt officer. Evidence was planted. Someone inside the police organization had to help. If Hae-young can identify that person, he may get closer to the reason Jae-han vanished.
The obvious name is Ahn Chi-soo.
Hae-young watches Ahn receive a courier note ordering him to Hansung Building’s parking lot about Lee Jae-han, with a warning not to use his phone. Hae-young confronts him, asking whether he framed Jae-han and who stood behind him. Ahn gives him nothing.
But the episode gives us the older shape of the rot. In 1997, Jae-han finds Kim Bum-joo’s name on a pyramid scheme investigation that somehow ended for lack of evidence despite two billion won in fraud. Bum-joo is already the kind of officer who knows where to bury a case before anyone calls it corruption.
Jae-han sees it.
He also keeps chasing ordinary criminals while the men above him chase comfort, numbers, and private advantage. The motorcycle mugger thread looks minor until it shows what Jae-han and young Soo-hyun are like when no one is watching. He pushes against orders. She follows a hunch from a dream and catches the right man. He calls her 0.5, but he also defends her when the squad laughs.
Their partnership is not sentimental in 1997. It is messy, rude, and still learning its own shape. That makes the later grief sharper.
Inju connects Hae-young’s brother to Jae-han’s disappearance
Hae-young asks Soo-hyun about Jae-han, Ahn Chi-soo, and Jinyang Precinct. She notices the pattern before he can hide it. The Kim Yoon-jung case, the South Gyeonggi murders, Han Se-kyu, and now Jae-han are all connected to the same missing detective.
Then she says the word that changes Hae-young’s face: Inju.
Jae-han met Ahn there while working the 1999 case involving a female high-school student. Hae-young knows Inju because it is his hometown. Ahn knows more: Hae-young’s brother, Park Sun-woo, was convicted as one of the offenders, served time in juvenile hall, and died by suicide soon after his release.
That information has been part of Hae-young’s file, used by adults who discuss his family history like an administrative complication. For Hae-young, it is the wound underneath everything. It explains his contempt for institutional comfort and his fixation on cases where the official version feels too convenient.
The episode does not resolve Inju here. It folds it into the same map as Jae-han’s disappearance. Jae-han investigated the case. Ahn was there. Hae-young’s brother was named as a perpetrator. Years later, Jae-han is missing, framed, and treated like a problem that must stay buried.
Hae-young is no longer investigating a dead detective as an outsider. He is walking toward his own family’s destroyed center.
That is also why the domestic detour at Soo-hyun’s home lands. Hae-young answers a possible burglary call and meets Soo-hyun’s mother, who mistakes the mess made by children for a break-in and then drafts him into household repairs. She asks his age, decides 27 is perfect, and keeps finding tasks for him.
Then Hae-young sees Jae-han’s old notebooks.
The list in the back links the cases we already know: South Gyeonggi in 1989, the 1995 larceny case, Hongwon-dong in 1997, and the 1999 Inju student case. These are not flashbacks for Hae-young. They are living pressure points. Every one of them has crossed his life through the radio, through police records, or through family damage.
When the radio opens again, Jae-han is in 1997. Two years have passed for him since the 1995 case. He has not met Ahn yet. He does not know Inju yet. Hae-young realizes there is still time before some of the worst damage occurs, but the rules do not give him comfort. The transmissions arrive in pieces, and every warning risks changing the wrong thing.
Jae-han finds the first Hongwon-dong pattern
The Hongwon-dong case begins with a woman and a dog.
A young woman feeds a white dog, helps a stranger look for it, and follows him into danger. The man speaks softly, almost tenderly. “It’s hard to live, right?” he says before violence closes around her. It is a horrible line because it is not random menace. He chooses women who are lonely, depressed, or isolated, then uses that loneliness as the door.
In 1997, Jae-han hears from Hae-young that Hongwon-dong is written in his future notebook, even though Hae-young cannot find a modern record of the case. Soon after, Jae-han visits Hongwon Police Station and sees a murder file: Joo In-hee, 37, found with a plastic bag over her head. A witness mentions a similar body in the next neighborhood a few months earlier.
Jae-han connects what the precincts missed. Joo In-hee and Yoon Sang-mi, 21, were found in different jurisdictions, handled by different police stations, and treated through narrower motives like insurance. Same body disposal. Same neighborhood range. Same killer.
Kim Bum-joo refuses to take the case. He has a language for refusal that sounds almost reasonable if you do not listen closely: too many people die, not every death can stop the department, nobody wants a serial murder case. Then he says the quiet part out loud. If the victims were daughters of congressmen or chaebols, the police would be moving differently.
Jae-han answers from the only place he knows how to live. He comes from a different world, one where people do not forgive murderers.
In 2015, the Cold Case Squad reaches the same file from the other direction. Soo-hyun raises Hongwon-dong during a case meeting. Two women were found over two months, less than a kilometer apart. Cause of death: asphyxia. Black plastic bags, rice sacks, bodies disposed of in a similar manner.
Hae-young is cautious with the serial murder label. He points out the FBI threshold: at least three victims, cooling-off periods, common characteristics. Then a new body is identified on Mt. Dongeui: Seo Yeong-jin, a Hongwon-dong resident who disappeared in 2001 at age 35.
Now the old two-body case has a third body, a changed burial method, and a present-day squad forced to ask what happened between 1997 and 2015.
Soo-hyun remembers surviving the Hongwon-dong killer
Soo-hyun knows more than she says.
Hae-young notices it after the remains are identified. She has already been looking for skeletal remains belonging to someone 185 centimeters tall with a metal plate in the shoulder. That is Jae-han. Her search for him has trained her to look at every unidentified body with dread and discipline.
But Hongwon-dong carries a second terror. Soo-hyun was there in 1997.
The procedural work leads to the memory. The victims differ in age, body type, job, route, and daily pattern. The one overlap is earphones and sad music. They are women walking through trash, flyers, concrete, steel, and the kind of loneliness nobody treats as evidence.
Young Soo-hyun follows those paths after reading Jae-han’s files. He finds her near the convenience store and tells her to go back. She tells him she feels bad for the victims. That is not naivete. It is the beginning of her detective instinct: she is trying to understand where their fear lived before the killer found them.
Then she becomes the third victim who lived.
Jae-han calls her home. She is not back. He searches. The killer has her bound, gagged, and terrified. He repeats the same soft cruelty. He tells her to be quiet, says she will be punished, and promises to make her comfortable. Jae-han reaches her in time, pulls her out, and apologizes because he was late.
“You did well,” he tells her.
That line matters for the next 15 years. Soo-hyun’s loyalty to Jae-han is not built from a crush alone, or from nostalgia for a senior detective who treated her kindly. It comes from this night too. He saw her fear, saved her life, and let her survive without turning her terror into shame.
In 2015, Soo-hyun believed the nightmare ended because no more bodies were found after her attack. The Mt. Dongeui search proves otherwise. Including Seo Yeong-jin, nine bodies are recovered.
The killer did not stop.
He hid better.
What works
The Hongwon-dong case is strong because the procedural details stay specific. The black plastic bags, rice sacks, broken hyoid bone, public disposal sites, changed burial method, earphones, and sad music all matter. Each detail moves the investigation and narrows the killer’s appetite.
Soo-hyun’s 1997 story gives the case its emotional force. Her present-day control reads differently after we see the attack. She has not been chasing Jae-han from a soft memory. She has been carrying a debt, a trauma, and an unanswered disappearance at the same time.
The Inju reveal also widens Hae-young without pausing the case. His brother’s conviction and suicide explain why official records never feel neutral to him. A file can be a weapon. A committee can call a family tragedy a background issue. A false accusation can outlive the person it destroys.
What stumbles
The early corruption thread is dense. Ahn Chi-soo, Kim Sung-bum, Kim Bum-joo, the courier note, the pyramid scheme report, and Jae-han’s framing all arrive before Hongwon-dong fully takes over. The pieces connect, but the viewer has to hold a lot of institutional rot while also absorbing a new serial case.
The lighter scene with Soo-hyun’s mother is charming, and it gives Hae-young access to Jae-han’s notebooks, but it bends close to sitcom rhythm right before the episode enters a brutal case involving sexual violence history, suicide, and serial murder. The tonal shift works because the notebook discovery is important. It is still a sharp turn.
What this sets up for Episode 10
Episode 10 has to deal with two clocks.
In 1997, Jae-han knows Hongwon-dong is active and has just saved Soo-hyun. He may still be able to catch the killer before more women disappear, but Hae-young’s present says nine bodies were eventually found. That gap is the nightmare.
In 2015, the Cold Case Squad has the remains, the pattern, and Soo-hyun’s buried knowledge. Ahn Chi-soo is also moving under orders about Jae-han, which means the old corruption story is no longer separate from the present investigation.
The radio can still open. The past can still hear a warning.
That has never meant anyone is safe.
Rating: 9.3/10
More episodes from Signal — Kim Eun-hee's time-bridge cold-case thriller, episode by episode. Jump to any episode in the season:
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Reviewed by Mira Vance · QuizFandom Editor & Lead Reviewer. Every rating is an honest per-watch assessment from the desk that also writes the quizzes — not a press release rehash.