In Episode 5 of "The Scarecrow," the story begins in 2019, with Si-young serving as one of his subordinate prosecutors. News reports announce the arrest of the Kangseng Serial Killer, leaving Si-young shocked. The episode then shifts back to 1988, where Sun-young wakes up in the hospital and learns that the killer attacked her. She frantically searches for Gi-beom before suddenly starting to bleed. The doctor reveals that Sun-young is pregnant, explaining the bleeding and assuring her that the baby is safe. Sun-young asks Ji-won to keep the pregnancy a secret from Tae-joo.
Meanwhile, Dae-ho finds Tae-joo outside the operating room where doctors are treating Si-young. He informs him that the serial killer has escaped. The doctor tells Tae-joo that Si-young has survived and is recovering well. Tae-joo rushes to meet Sun-young and asks if she is helping Gi-beom.
Sun-young finally reveals the truth to Tae-joo and Ji-won, explaining how she stopped Gi-beom from turning himself in for Kyung-ho's assault. She also explains how Gi-beom locked her in a room before fleeing and how she chased after him before the serial killer attacked her. Tae-joo expresses concern about his sister's involvement with Gi-beom. As Sun-young is discharged from the hospital, Tae-joo asks Ji-won to stay with her. Back at the house, Ji-won finally tells Sun-young that Gi-beom is now a suspect in the serial killer case.
Elsewhere, Sang-beom visits the hospital to check on Si-young. He gets angry at Tae-joo, assuming he shot Si-young. Tae-joo asks Sang-beom to contact Si-young's parents, only to learn that Si-young lives alone and is distant from his family.
Tae-joo goes through Si-young's phonebook and calls Cha Jun-young, assuming he is related to Si-young. However, Tae-joo is shocked by Jun-young's cold reaction to the news about his younger brother.
The next morning, Ki-hwan calls Gi-beom's friends to check if he is hiding with them. Tae-joo helps Ki-hwan's wife and mother carry groceries into the house. Ki-hwan is surprised to see him there and asks Tae-joo to keep Gi-beom's arrest a secret. Outside, Tae-joo explains that Gi-beom still needs to sign papers at the station because Kyung-ho dropped the assault charges. Ki-hwan thanks Tae-joo for helping his family.
Back at the station, the detectives discuss the case. Hyung-gu and Myung-do pressure Man-chun into pursuing Gi-beom as the serial killer, but Tae-joo and Dae-ho insist on waiting until Si-young wakes up. Just then, another murder is reported. The detectives arrive at the scene and discover a young girl murdered in her bed. Tae-joo studies the body and concludes that the murder does not match the serial killer's MO. Outside the house, the girl's parents blame themselves and the police for failing to protect the citizens of Kangseng.
Elsewhere, Myung-do scolds Hyung-gu for allowing Gi-beom to escape. A flashback reveals that Hyung-gu arrested Gi-beom outside the victim's house the previous night. However, while Myung-do prepares to drive them back to the station, Hyung-gu steps out to relieve himself. Gi-beom frees himself and escapes from the police car.
The following morning, the detectives debate whether they should confess the truth to Man-chun. Meanwhile, the media and locals gather outside the victim's house and blame the police for the murder. Man-chun takes responsibility, apologizes to the public, and asks for more time to investigate.
At the Kangseng Police Station, Chief Park Eun-kyu learns of his transfer due to his failure to solve the murders. Man-chun is also transferred, leaving Tae-joo, Dae-ho, Myung-do, and Hyung-gu under Jun-young's authority as the new section chief. The detectives bid farewell to Man-chun, while Tae-joo misses the gathering. He later meets Man-chun privately, gifts him a new jacket, and says goodbye. Before leaving, Man-chun advises Tae-joo to trust his colleagues instead of carrying every burden alone.
Later, Jun-young asks whether the young girl's murder is connected to the serial killings. Tae-joo explains that the victim's age and the different modus operandi rule out the murder from the serial killer case. However, Myung-do and Hyung-gu finally confess that they lost Gi-beom outside the victim's house. Tae-joo is disappointed that they hid this information from him before informing Jun-young.
Meanwhile, Jun-young visits Si-young at the hospital under their father's orders. He explains that their father wants both sons to present a united front while solving the case. Si-young is disgusted by the sudden concern. A flashback reveals Si-young's father violently beating him for ranking second in school. Jun-young mocks Si-young for being their father's illegitimate son.
Back in the present, Si-young watches Jun-young speak with Tae-joo outside the hospital. Tae-joo asks Jun-young to make him the new task force leader. When Jun-young insults Tae-joo's upbringing, Tae-joo immediately fires back, surprising Si-young.
Inside the hospital room, Tae-joo asks Si-young whether he saw the killer's face during the attack. Si-young urges Tae-joo to consider Gi-beom a suspect because of the evidence against him. Tae-joo admits that even more evidence now points toward Gi-beom.
Elsewhere, Sun-young wakes up from a nightmare about the killer dragging her body. She insists to Ji-won that Gi-beom would never hurt her. That night, Myung-do and Hyung-gu secretly torture Gi-beom in hiding. It is revealed that they lied about his escape because they wanted more evidence before bringing him to the station.
The next morning, Ki-hwan searches the town for Gi-beom. Gi-beom's friend Im Seok-man avoids Ki-hwan to keep the truth hidden. A flashback reveals that Seok-man witnessed Myung-do and Hyung-gu arresting Gi-beom the previous night while Myung-do threatened him into silence.
Meanwhile, Sun-young and Ji-won arrive at Gi-beom's house to speak with his mother. Moments later, detectives arrive with a search warrant. Ki-hwan feels betrayed by Tae-joo, while his mother calls Tae-joo ungrateful after everything she did for him and Sun-young.
Sun-young suddenly gets sick, leading Tae-joo to discover her pregnancy. She tells her brother that Gi-beom is not the man who attacked her and reveals that the real attacker limped while dragging her body. The detectives later discover Ae-sook's bag in the library, directly linking Gi-beom to the murder. They also show Tae-joo an old photo of himself and Gi-beom from a mutual friend's wedding. Tae-joo notices the wedding date and rushes back to the station to check the files. There, he realizes that Gi-beom was with him during one of the murders, proving his innocence in at least one case. However, the remaining evidence against Gi-beom leaves Tae-joo conflicted.
Later, Tae-joo runs into Ki-hwan, who accuses him of lying about protecting Gi-beom. During the conversation, Tae-joo realizes that Ki-hwan also had access to both the library and the house, making him a possible suspect as well.
The episode moves back to 2019, where Sun-kyung visits Yong-woo in prison on Tae-joo's behalf. Yong-woo refuses to speak to her and demands to meet Tae
