Chen Kaiqing’s father visits her and she expresses her decision to stay and investigate the case instead of returning to Canada. He supports her decision and lets her go. Back home, he reminisces on the balcony, worried about losing his daughter to someone else.
Informed of a new lead, Yang Guangyao takes Chen Kaiqing to question Mrs. Zhong. She remains fearless and denies recognizing the person in the sketch, asking to be left alone. Yang Guangyao finds her suspicious, particularly her use of earphones, but is stopped from further questioning. Later, they use aerial surveillance and locate Mai Zhihong hiding in a villa.
Inside the villa, Mrs. Zhong pleads with Mai Zhihong to spare her child. Mai Zhihong blames her for past actions. Yang Guangyao bursts into the room and orders him to release the child. Outnumbered, Mai Zhihong throws the child aside and flees. Yang Guangyao chases him, jumps into his car, and after a struggle, the police subdue and arrest Mai Zhihong.
Yang Guangyao and his team question Mrs. Zhong again, hoping to learn more about Mai Zhihong. She reveals some information but claims to know nothing about the tutor.
In the hospital room, Yang Guangyao watches Mai Zhihong eat. He then replaces his handcuffs with a dog leash, making Mai Zhihong visibly nervous. Mai Zhihong’s alternate personality briefly emerges, almost revealing the tutor’s identity, but he quickly regains control and refuses to cooperate, taunting Yang Guangyao about his inability to protect his loved ones.
Although the cases are seemingly solved with Mai Zhihong’s arrest, Yang Guangyao remains unconvinced. He feels there’s more to the story, especially with the tutor’s identity still unknown. He decides to investigate further.
Dr. Zhou visits Mai Zhihong in detention and encourages him to reveal the tutor’s name. Meanwhile, Yang Guangyao receives the medical report and notices something unusual. He rushes to Mai Zhihong, lifts his shirt, and finds a scar near his navel. He becomes suspicious and questions someone who worked with Mai Zhihong in the past. He learns that Mai Zhihong was installing air conditioners at home during the relevant period and couldn’t have been involved in the crimes. Yang Guangyao decides to revisit the unchanged sewer.
On the way, Yang Guangyao shares his suspicions about the forensic examiner, Dr. Chen, with Zhang Tianming. He points out how Dr. Chen’s arrival coincided with breakthroughs in the case and Mai Zhihong’s capture. Fearing for Chen Kaiqing’s safety, they decide to remain vigilant.
Back at the police station, Yang Guangyao’s superior reprimands them for coercing a confession. However, Yang Guangyao insists there’s more to the story. They keep a close watch on Mai Zhihong, worried that someone might try to silence him. Chen Kaiqing learns about their investigation into her father and angrily confronts them. She vows to clear her father’s name and find the truth. Later, she sends caring messages to her parents, which her father sees while eating.
