In GG Precinct, a group of officers investigates a series of murders with the help of a convict, facing numerous mishaps and setbacks along the way. The series is now streaming on Netflix.
Warning: This article contains heavy spoilers
Plot summary
Detective Wu Ming-han, who was shot in the line of duty, returns to work after recovering, only to discover that Lin Tzu-ching, who was undercover on the same case, has been promoted to captain.
Their former captain, Chang Yung Kang, is now the station chief. Other officers at Gia Gun Precinct include Chubby, Li Shu-fen, and Shao-nien, an officer who became a drug addict after an undercover assignment.
Ming-han is impulsive, short-tempered, and driven more by instinct than logic. He is unhappy about Tzu-ching’s promotion, believing that he deserves it more.
He does not acknowledge the fact that Tzu-ching works tirelessly to prove her worth and avoid being underestimated as a woman. Tzu-ching and Ming-han’s lack of mutual respect causes friction between them.
When a watchman is murdered at his workplace, the case falls under the Gia Gun Precinct’s jurisdiction, forcing Ming-han and Tzu-ching to work together.
The crime scene is unusual, and Chief Chang notes similarities to a case he solved twenty years ago, known as the Idiom Murders Case.
In that case, a Chinese teacher named Shui-yuan killed two students who wrote the wrong words on their idiom exams. The teacher arranged their bodies to depict the incorrect idioms.
Chief Chang believes that the watchman’s murder is similar to the Idiom Murders. Soon after, the body of a PE teacher is found, also arranged to depict an idiom.
Ming-han and Tzu-ching interview Shui-yuan, who quickly deciphers the idioms the killer intended to portray and warns Tzu-ching that more murders will follow.
Shui-yuan’s prediction proves correct when a third victim, an idol named Mogi Yumi, is found dead, her body arranged to depict an idiom Shui-yuan wrote on his wall after meeting Tzu-ching.
Yumi’s manager, Lin Pai-sheng, suspects Hsieh Cheng-ta, a fan of hers. When he informs the police, they search Hsieh Cheng-ta’s house for clues.
Ming-han, on the other hand, decides to act alone. Without informing Tzu-ching, he goes to Yumi’s house, hoping to catch the killer.
He arrests Lin Pai-sheng, convinced that he is the murderer, but not without sustaining injuries. Later, Hsieh Cheng-ta also turns himself in, claiming that he is innocent.
Tzu-ching questions Shui-yuan again, who reveals that he knew the idiom the killer was going to depict next because the killer is following the order of idioms from his idiom supplement.
During the interrogation of Lin Pai-sheng, Ming-han learns about a Chinese teacher, Huang Hsien, who taught Yumi. Ming-han now suspects Huang Hsien, while Tzu-ching suspects Lin Pai-sheng.
Their disagreement escalates into an argument where Ming-han accuses Tzu-ching of betrayal and humiliates her in front of everyone.
Ming-han, realizing that he went too far, later apologizes. This leads to the two of them finding common ground and finally working together.
Ming-han follows Huang Hsien and sees him on a date with a student, Liu Mu-ting. The date is interrupted by another woman. Ming-han arrests Huang Hsien after discovering that he was Shui-yuan’s assistant.
Shui-yuan is brought in to confront Huang Hsien, but Huang only admits to inappropriate relationships with students, denying involvement in the murders.
That same night, Liu Mu-ting is murdered, becoming the fourth victim. A delivery person wearing a helmet is seen entering her apartment, making Hsieh Cheng-ta a suspect once again.
However, Hsieh Cheng-ta has an alibi, and with Huang Hsien and Lin Pai-sheng in custody at the time of the murder, the police are left without any suspects.
Ending explained:
The failures of the officers
As the pressure to catch the serial killer mounts on the officers of Gia Gun Precinct, Chief Chang has no choice but to follow the Police Commander’s orders.
He is instructed to lay a trap for the killer, and he decides to become the bait himself by deliberately writing a wrong idiom on national television.
Chief Chang then orders food, hoping that the killer will come to deliver it. He prepares for the encounter with a team of officers watching closely.
The killer arrives, but just as Chief Chang is about to attack them, he slips, hits his head, and passes out. He is then kidnapped by the killer right under his team’s noses.
Meanwhile, Tzu-ching and Ming-han struggle to understand why Liu Mu-ting was targeted; she was a top student who never made mistakes in her writing.
When they consult Shui-yuan, he convinces them to take him to her house to look for clues they might have missed. Once there, Shui-yuan manages to trick them and escape.
Ming-han attempts to stop him but ends up in another car accident. Both he and Tzu-ching fail in their tasks, as do the officers responsible for protecting Chief Chang.
Who is the killer?
Shao-nien gets an eyewitness of the first murder to talk to him and discovers that the delivery person seen before the murder was a woman.
Ming-han, who survives the accident, realizes that the killer is the second woman he saw with Huang Hsien while tailing him. That woman also happens to be a delivery person.
He now recognizes her as someone who frequently delivered food to Chubby at the precinct. The officers then question Huang Hsien about the woman.
They learn that she is his younger sister, Hsiao-yin, who was also taught by Shui-yuan. Hsiao-yin was an exceptional student who took Shui-yuan’s teachings to heart.
She could not tolerate disrespect toward him or her brother. Even as a child, she had attempted to kill two of Shui-yuan’s students for disrespecting him and bullying her brother.
Shui-yuan had stopped her at the time, only to kill those students himself later. Hsiao-yin is now following in her teacher’s footsteps.
Tzu-ching and Ming-han manage to get Huang Hsien to reveal Hsiao-yin’s possible whereabouts and rush to save Chief Chang before it is too late.
The death of the serial killer
Shui-yuan also figures out that his devoted student, Hsiao-yin, is the murderer. When the police had suspected Huang Hsien, he deliberately diverted their attention.
He now goes to the swimming pool where he used to go with Huang Hsien and Hsiao-yin. As expected, he finds Hsiao-yin there.
Hsiao-yin admits to him that she wanted to preserve Shui-yuan’s teachings, feeling that her brother had failed by focusing more on dating his students than on education.
Hsiao-yin explains that she killed the watchman and the PE teacher because they made mistakes in their use of idioms and refused to learn when corrected.
Yumi, who was dating Huang Hsien, also misused idioms. However, Liu Mu-ting was different; she made no mistakes, but Hsiao-yin killed her to teach her brother a lesson.
Shui-yuan disapproves of Hsiao-yin’s decision to kill Liu Mu-ting. He believes that Hsiao-yin has lost her way and that she cannot find herself by imitating him.
He prevents her from killing Chief Chang to correct her mistake, leading Hsiao-yin to take her own life to complete the idiom she depicted using Liu Mu-ting’s body.
By the time Tzu-ching, Ming-han, and the other officers arrive there, Shui-yuan has already fled. Chief Chang is rescued, but Shui-yuan is nowhere to be found.
Eventually, the Police Commissioner takes credit for solving the case, while Ming-han and Tzu-ching are blacklisted for allowing Shui-yuan to escape.
In the final scene, Shui-yuan is seen enjoying his freedom. It is hinted that he will continue killing people.