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.

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.

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

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

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.

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.