Gap-dong

Mu-yeom who became a detecitve for his father, receives news like a nightmare.

On Christmas Eve, a woman returning home alone is murdered; hearing there is something suspicious about the body, Mu-yeom rushes to the crime scene.

While Mu-yeom blacks out after Tae-oh's attack, a newspaper office receives a call reporting that the first case is the act of Gabdong and warns there will be a second case of murder. At last, Mu-yeom gets accused as the person who reported the case.

Mu-yeom is arrested as a criminal caught in the act and is cornered as a suspect of the second murder case; Chief Yang suggests they compare the DNA of Gabdong and Mu-yeom.

Chief Yang meets Maria and thinks of a girl he met at the scene for a case from a while ago.

Mu-yeom suspects Tae-oh is Gabdong; Tae-oh meets up with Maria and tells the story of his father.

The civilians blast anger and attack at the police for failing at preventing the fourth case.

Gunshot fires and someone passes out. Chief Yang and detectives express astonishment and come running. Meanwhile, the civilians blast anger and attack at the police for failing at preventing the fourth case.

Mu-yeom, who finds a corpse, runs at Tae-oh with a violent temper; Maria witnesses an unbelievable sight in Choi's room; Chief Yang takes responsibility for not preventing the fifth case.

A phone call rings from the real Gabdong; Mu-yeom learns the true identity of Gabdong.

A phone call rings from the real 'Gabdong,' in the center. Mu-yeom finally gets to know the true identity of Gabdong.

Gabdong finally gets caught. Mu-yeom starts the interrogation and goes as far as lifting a hammer to get his shut mouth talking.

Tae-oh confesses his crimes; Maria is in shock after learning that Gabdong is probably dead; Mu-yeom runs to the crime scene after getting a call that the remains of an unknown person are found and sees something unusual.

Tae-oh starts confessing his crimes, and Maria falls in shock after finding out that Gabdong is probably dead. Meanwhile, Mu-yeom runs to the crime scene after getting a call that the remains of an unknown person are found and sees something unusual.

Mu-yeom and Tae-oh race to the end of the cliff; Do-hyeok makes Ji-ul, who seems to be in a good mood on her way to work, get in his car.

Mu-yeom and Tae-oh, neither one of them slows down and races to the end of the cliff. Meanwhile, Do-hyeok makes Ji-ul, who seems to be in a good mood on her way to work, get in his car.

While searching Do-hyeok's house for evidence, Mu-yeom finds a picture frame of the Eiffel Tower, which seems suspicious; Ji-ul makes up her mind and heads to meet Tae-oh.

Tae-oh makes a deal between Do-hyeok and Maria; Mu-yeom collects the two Gabdongs in one place; the trial of Gabdong airs live through the nation.

Maria arrives at the arboretum; Tae-oh reenacts the ninth case with Ji-ul and Maria; a gunshot rings at the pool Mu-yeom and Do-hyeok are at, and someone begins bleeding.

The trial of the two Gabdong finishes, with hard choices to make; the two fall into a dilemma.