Season 1

Yoo Dong-man goes undercover to root out illegal gambling. Kang Sun-ho steals money from criminals to pay for his father’s cancer treatment.

Oh Kang-hui witnesses her mom’s arrest. When training begins at the university, Dong-man appoints Sun-ho a leader, set on flunking him.

Determined to bring victory to his team, Sun-ho asks Dong-man for advice. The final assignment comes with a twist.

Sun-ho gets grilled in class. Kang-hui’s personal life is made public on the school website. Dong-man feels out the police chief.

Dong-man grows suspicious of a fellow professor. With Sun-ho by his side, he scopes out the scene of the crime to check out an alibi.

Another potential culprit appears on Dong-man’s radar. Sun-ho struggles to remember the events of the night before. The campus hosts a field day.

Sun-ho finds Park Cheol-jin suspect, but Dong-man is determined to keep him off the watch list. Kang-hui attends her mom's trial.

Cheol-jin finds himself in an even deeper rut when he's cornered by Sun-ho and Dong-man. A cheating scandal breaks out during the final exams.

Cheol-jin falls into a trap. Dong-man takes a closer look into Ko Deok-bae’s business. Kang-hui insists on joining Sun-ho in the investigation.

Sun-ho and his friends track the location of the burner phone. The professors step in to protect their students from further danger.

Sun-ho gets Kang-hui a gift, but hesitates to give it to her. A critical piece of evidence is missing. Dong-man spots a colleague at the precinct.

Sun-ho’s criminal history comes back to haunt him. Learning of Choi Hui-su’s connections to the case, Dong-man leans on his gut and tails her.

Sun-ho acquires a key to a safe, Kang-hui calls it quits and Dong-man gets eyes on the chief. Stronger curfews and regulations are enforced on campus.

With his hands on the ledger, Dong-man is sure that he's pinned down the culprit. Sun-ho gets arrested for conspiring with Jang Jae-gyu.

The police look for incriminating evidence against Han Jeong-sik. The truth behind the foundation finally comes to light.

Sun-ho completes one final hacking job before dropping out of school. He turns himself in for his past crimes so he can return with a clean slate.