The seventh episode of Doubt opens with Jang Tae-su stumbling upon his daughter, Ha-bin, standing over Choi Yeong-min’s lifeless body, her hands stained with blood. Panic sets in as the police arrive at the scene, but Tae-su manages to flee with Ha-bin and one of the weapons used in the crime. Back home, despite Ha-bin’s insistence on turning herself in, Tae-su forces her to stay put. She then reveals a shocking truth: Ji-su, her mother, took her own life out of guilt after burying Su-hyeon’s body, mistakenly believing Ha-bin was the killer.
As Ha-bin changes out of her blood-stained clothes, Tae-su hides them in a drawer alongside a small gift box. When he asks if she saw who really killed Yeong-min, Ha-bin denies knowing anything.
Tae-su later returns to the crime scene, carefully examining photos of Yeong-min’s body. He deduces that two different weapons were used, meaning there might be two culprits. Nearby, he finds a pendant necklace, which Eo-jin, a police officer, notices and collects as evidence. Eo-jin suspects one of the culprits might be a woman.
Meanwhile, Joon-tae’s father informs him that Ha-bin killed Yeong-min, sparking an argument about Joon-tae’s relationship with Sung-hee, a single mother. Despite Joon-tae’s efforts to defend Sung-hee, his father remains adamantly opposed.
Elsewhere, Ha-bin contacts Song Min-a’s youth shelter and learns her parents have passed away, confirming that the man posing as Min-a’s father is a fraud. At the police station, the team discusses Sung-hee’s potential involvement after a necklace was found at the crime scene. Another officer notes that Joon-tae might have met Song Min-a on the day of her death. Alarmed, Tae-su confronts Joon-tae, who claims he can’t remember the details but implicates Ha-bin’s presence at Yeong-min’s murder scene.
Eo-jin discovers that Tae-su was the last person to speak to Yeong-min before his death. At the same time, Joon-tae’s father, Du-cheol, confronts Sung-hee about Song Min-a’s death. Sung-hee recounts that Min-a had come to her house to collect her belongings after leaving Yeong-min’s gang. When Sung-hee returned from a doctor’s visit with her ill son, she found Min-a dead on her bed, with Joon-tae sitting nearby. Du-cheol refuses to believe her story but leaves when the police arrive.
Back at the station, suspicions grow around Tae-su, as Eo-jin suggests his behavior is tied to Ha-bin’s involvement. Although Ha-bin’s alibi checks out, her actions remain suspicious. Meanwhile, Ha-bin secretly burns her blood-stained clothes and visits the police station to find Du-cheol’s real address and identity.
Joon-tae, torn between his relationship with Sung-hee and his father’s demands, ends things with her and confesses that he met Yeong-min on the day of his murder. Later, the police arrest Sung-hee after finding CCTV footage placing her near the crime scene. Watching from a distance, Joon-tae decides to turn himself in. At the station, he hands over the weapon he claims was used to kill Yeong-min.
In another CCTV clip, Tae-su spots Ha-bin riding on a motorcycle behind a man wearing a helmet. At home, he notices the necklace found at the crime scene in an old photo of Ji-su.
As the episode nears its end, Du-cheol recalls seeing Ha-bin at the murder scene and becomes convinced his son, Joon-tae, is innocent. Tae-su confronts Ha-bin about the man on the motorcycle, but she refuses to answer. When he threatens her with handcuffs, she coldly vows to find and kill everyone responsible for her mother’s death.
In the final moments, Tae-su receives a shocking photo from Ha-bin’s number, sent by Du-cheol. The image shows Ha-bin standing next to Yeong-min’s body. Du-cheol then calls, demanding Joon-tae’s release in exchange for keeping the photo a secret.
The eighth episode of Doubt starts with Jang Tae-su confronting his daughter, Ha-bin. Tae-su pleads with her to stop her revenge plans, blaming her actions and doubts for her mother Ji-su’s tragic death.
At the police station, Tae-su interrogates Joon-tae, who confesses to killing Yeong-min to protect Sung-hee. However, Detective Eo-jin isn’t convinced. Circumstantial evidence points to two people being involved in the murder. Tae-su then receives a shocking photo of Ha-bin standing over Yeong-min’s corpse, sent by Joon-tae’s father, Du-cheol, who blackmails him to secure Joon-tae’s release.
Eo-jin grows suspicious of Ha-bin and confronts her about her connection to Lee Su-hyeon and Yeong-min, but Ha-bin denies knowing anything. Meanwhile, the police discover Du-cheol’s involvement, suspecting him of moving Song Min-a’s body. The tension rises as Tae-su realizes Du-cheol is Joon-tae’s father, but the connection remains unclear.
Later, Joon-tae confesses to murdering Song Min-a, claiming he strangled her. But the police uncover discrepancies—Min-a wasn’t strangled. This revelation, along with new evidence linking Ha-bin to the crime scene, shifts suspicion toward her.
The episode ends on a cliffhanger as Tae-su is handed damning evidence—a photo of Ha-bin at the crime scene, officially marking her as a suspect in the ongoing murder case.