
7.6
A romantic investigative drama about rookie detective Yoo-Ryung who solves cases with her overflowing sense of justice and exceptional spatial perception but always gets herself into trouble because of her rash actions. She meets the Wangsimni station constabulary chief, a man who avoids cases and seeks stability who always ends up cleaning up after the problems caused by Yoo Ryung and holds the key to solving the cases.
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1Episode 1Job Interview & Audition
69 min
The Subway Police of Wangsoori Station is led by Chief Inspector Ko Ji Seok. He is the best of the best, although his only goal in life is to have a stable, uneventful career. However, a serial killer, nicknamed “the Subway Ghost”, strikes the Subway Police 30 Year Anniversary event. An applicant shows up for a job interview to join the team.
2Episode 2Going Home to Family
66 min
Ryung officially becomes a member of the Wangsoori Subway Police and Ji Seok’s partner. Ryung gets into trouble from the start, because she sneaks into the tunnels. Meanwhile, an elderly man who delivers packages via subway becomes the victim of an assault. Ji Seok realizes that the package is related to criminal activities. While Ji Seok wants to hand the case over, Ryung acts before she thinks, as always.
3Episode 3Disciplinary Hearing
64 min
Ryung and Ji Seok attend the disciplinary committee hearing and return to the station for night duty. Thanks to Ji Seok’s martial arts demonstration and a pot of noodles, Ryung gets her hands on the screen door keys once more. Meanwhile, an ordinary father, whose livelihood takes place on the subway, goes missing.
4Episode 4Tracking Down the Grasshoppers
67 min
Ryung and Ji Seok save Choi Do Chul just in time. Throughout their investigation, Ji Seok miraculously learns to appreciate Ryung’s over-the-top nature. Meanwhile, a star professional fighter becomes the PR Ambassador for the Subway Police. By chance, Ryung comes across his dirty secret and the Wangsoori Subway Police finally get a lead on the Grasshoppers.
5Episode 5Club Day
68 min
Ji Seok makes up his mind to kick Ryung out of the Subway Police for taking investigations into her own hands all the time. However, Ryung is attacked while out on an investigation by herself and there is something weird about the man who seems to be following her. Meanwhile, the Wangsoori Subway Police get dressed up to go out on Club Day, the best day to boost their arrest records.
6Episode 6A Petty Thief?
60 min
A rumor circulates about people disappearing after they party all night on Club Day, then taking the first train home. Ryung and Ji Seok get on the first train to find out whether the rumor is true. During their train ride, they run into a suspicious petty thief and the truth about the first train rumor comes to light. Meanwhile, Ryung finally meets the Subway Ghost a month after joining the Subway Police.
7Episode 7Jealousy & Confusion
65 min
Subway Police and the Metropolitan Detective Division come together for a joint investigation. Despite Ji Seok’s jealousy, the joint investigation team switch partners. Ji Seok and Ma Ri become one team, while Ryung and Woo Hyuk become another. Meanwhile, Ji Seok decides to let Ryung transfer to a different team. As Ma Ri approaches him again, Ji Seok feels confused.
8Episode 8Facing the Harsh Truth
60 min
Ma Ri leaves Ryung after saying harsh words that keep replaying in Ryung’s mind. Still, Ryung continues her search for the Subway Ghost. But this time, she comes across someone willing to help. Meanwhile, an autistic boy goes missing from the bakery in Wangsoori Station and the Grasshoppers are on a pickpocketing spree once again. Ji Seok and Ryung have different priorities in which case to pursue.
9Episode 9Getting Closer to the Subway Ghost
61 min
Ryung and Ji Seok work together to save Jung Hoon and catch the kidnapper. With their great partnership, they discover the identity of the person who helps the kidnapper hide from the police. Meanwhile, the Subway Ghost marks his next target and Ryung activates her subway search skills to track him down.
10Episode 10The Hideout
67 min
The Subway Ghost’s hideout is finally uncovered. Through the evidence found in the hideout, the police slowly start to piece together the Subway Ghost’s identity. Meanwhile, Ryung’s illegal investigations in the tunnels come to the attention of the commissioner and Ji Seok faces the biggest crisis in his career.
11Episode 11Going After the Grasshoppers
61 min
The police make headway on the Subway Serial Murders and narrow down the suspect list. After getting a tip about the identity of one of the Grasshoppers, Ryung and the Metropolitan Detective Division chase him down as he might be the Subway Ghost. Meanwhile, Ji Seok’s investigative instincts start acting up again, despite his suspension.
12Episode 12The One that Got Away
61 min
One of the Grasshoppers gets away from the police. The other two Grasshoppers confess that they only know him as Han Tae Woong, although that name turns out to be a fake identity. The investigation reaches a dead end and Ji Seok is about to be reassigned to a remote island. Ryung comes up with a plan to save Ji Seok and to catch the Subway Ghost.
13Episode 13The Grasshoppers Are Behind Bars
62 min
Ji Seok and Ryung catch the remaining Grasshopper who everyone believes is the Subway Ghost. However, while being interrogated, the Captain of the Grasshoppers makes a shocking statement. The truth about the Subway Serial Murder Case finally begins to reveal itself and Ryung is hopeful that she may find out what happened to her sister.
14Episode 14The Subway Ghost Reveals Himself
59 min
The police believe the Subway Ghost is in a mental hospital and that he plans to commit another murder. They chase him down and search the entire hospital building. Amid the chaos, Ji Seok’s mom and her caretaker are nowhere to be found. The Subway Ghost leaves behind a video clip, revealing himself and the shocking truth.
15Episode 15The Subway Ghost’s Method
61 min
Ryung and Ji Seok make their way into Kyung Hee’s house and find a room that looks like a young girl’s. After sharing the new evidence with Ma Ri and her team, they split up into two groups to chase both Kyung Hee and Yi Joon. Meanwhile, Ryung’s hopes of finding Jin alive begin to grow and Ji Seok gets a call from the hospital about his mom.
16Episode 16Finally Catching the Subway Ghost
61 min
Finally, Ryung and the Subway Ghost come face to face. As his rage explodes, the Subway Ghost attacks Ryung, but another tragedy puts a stop to his actions in the end. Meanwhile, Jin appears at the scene, only to run away amidst the chaos. Ryung, the Subway Police, and Ma Ri’s team put in all their efforts into reuniting the twin sisters.

Moon Geun-young
Yoo Ryung

Kim Seon-ho
Ko Ji-Seok

Jung Yoo-jin
Ha Ma-Ri

Jo Jae-yun
Lee Man-Jin

Ahn Seung-gyun
Kang Soo-Ho
Han Ji-sang

Lee Jun-hyeok
Chief Kong

Song Ok-suk
Kim Hyeong-Ja

Ahn Sang-woo
Jeon Won-Chool

Nam Kee-ae
Han Ae-Sim

Kim Jung-young
Choi Kyung-Hee

Song Sang-eun
Park Mi-Hyun