1. Episode 1

In need of a big win at work, Na Je-hui plays on Koo Kyung-yi's strengths and weaknesses to enlist her help on a missing person's case.

2. Episode 2

Kyung-yi suspects there's more to this accident than meets the eye. Reuniting with an old classmate, Song Yi-kyung hears about a former teacher's fate.

3. Episode 3

A news story about a criminal's light sentence establishes the next target for "K," who sets the scene at a bustling university campus.

4. Episode 4

Santa's chase after "K" puts the team on high alert, especially Kyung-yi. A spooked co-conspirator distances himself from the criminal mastermind.

5. Episode 5

Jung Jeong-yeon thinks back to a traumatic incident in her niece's past. Following a hunch that "K" might leave the country, Kyung-yi's team sets a trap.

6. Episode 6

Kyung-yi sifts through Yi-kyung's playbooks to find out the next target. An outcast's account takes the team to an IT company headed by a public figure.

7. Episode 7

In a high-stakes game of cat and mouse, Kyung-yi tries to find and stop the deadly plans Yi-kyung has set in place for Ko Dam's public event.

9. Episode 9

Yi-kyung joins hands with Yong-suk, replacing a down-in-the-dumps Kyung-yi who falls out of favor with the strong-handed director.

10. Episode 10

Kyung-yi inches closer to finding out the truth behind the boat party. Yi-kyung tries to escape the suffocating grasp of Yong-suk's control.

11. Episode 11

Yong-suk begs for Kyung-yi's help after a video of the yacht party is leaked. Yi-kyung taps a member of Kyung-yi's team for a covert collaboration.

12. Episode 12

Santa is held hostage by Yi-kyung, who reveals his identity to a disbelieving Kyung-yi. Yong-suk's plans blow up in her face.