Undercover

Jeong-hyeon(Ji Jin-hee) and Yeon-su(Kim Hyun-joo) first met at a protest in 1991 and are now 20 years into their marriage. They enjoy peaceful lives working as a human rights attorney and running a bike lab. As Yeon-su helps Jeong-ho(Choi Kwang-il), a man wrongly put in prison, Jeong-hyeon tends to home duties and their austistic son. One day, he meets a man who remembers the name “Lee Seok-gyu”.

He has to deceive and stop his wife for his family! Is this perhaps his punishment for the life he’s led. Jeong-hyeon and Yeon-su can’t seem to open up to each other, and he has to face those who are against his wife’s appointment to be head of the CIO. Meanwhile, a woman comes to her for help with the case of her late husband. She starts on the case, not knowing what chaos this is about to bring.

Hyeong-rak (Huh Joon-ho) conspires against Yeon-ju’s run for CIO directorship while Jeonghyeon offers his support to her despite her hesitance. But soon they face threats aimed at their son, Seung-gu(Yoo Seon-ho). As soon as Yeon-su enters the Blue House, she receives a letter from the late Cha Min-ho(Nam Seong-jin) and asks her husband to check it.

As Seung-gu’s violent actions hit the news, Yeon-su is about to lose CIO directorship. As the world gossips about her son’s alleged wrongdoing, she is now forced to make a decision for the bigger cause. Jeong-hyeon looks into Project “Strike Gold” and finds out about the involvement of several agents in the past and has to tell another lie to Yeon-su. Meanwhile, she finds out about her opposition.

Upon witnessing Yun-ju’s (Han Go-eun) despair over Min-ho’s death, Jeong-hyeon cannot help but feel sympathetic. A mysterious death, a former colleague, and her past that she’s kept hidden. And what is Project Strike Gold? Jeong-hyeon uses Yeong-geol to find out who’s behind it. Yeon-su only has hearing left. She remains calm answering questions, and then a sudden revelation shakes up the room.

Yeon-su now finds herself cornered at the hearing and proclaims that she’ll take responsibility. Her opposition now discusses her resignation, but her mouth remains clamped. As Jeong-hyeon goes after the truth behind “Project Strike Gold”, he notices Yeong-geol’s(Jung Man-sik) suspicious actions and feels threatened. Upon finding out Yeon-su is in danger, he moves out to save her.

On her first day in office, Yeon-su receives a report that Head Secretary Kim Myeong-jae(Jung In-gi) received a substantial amount of bribe. She has to conduct an investigation against her most trusted supporter and feels that this may be a trap. Yeong-geol joins the CIO as head of the security team and is now able to interfere with Yeon-su’s actions. Jeong-hyeon feels that he needs to step up.

A spy camera scandal shakes up the CIO. Yeon-su is faced with a dilemma as her opposition will benefit from Kim Myeong-jae’s dismissal. She announces that evidence proves his innocence and that the allegation was false. However, when she makes the announcement, the press conference becomes astir. Meanwhile, Park Du-sik, the murderer of Kim Tae-yeol, reaches out to Jeong-hyeon.

Yeon-su orders an arrest for Kwak Mun-heum, the head prosecutor who ordered confiscation of the evidence for Myeong-jae’s case. She needs the evidence back within the 48 hours she can keep him detained. He refuses to speak as Yeon-su interrogates him, and the CIO staff are worried. Meanwhile, Jeong-hyeon is framed for murder and cannot return home. His family starts noticing that he has changed.

Yeon-su sees Jeong-hyeon embracing Yun-ju and starts suspecting he’s having an affair. His reaction is calm as if he has done nothing wrong, but her suspicions grow clearer. Meanwhile, Yeong-geol discovers that Jeong-hyeon has been watching him and tries to trap him. Yeon-su receives a suspicious audio recording and starts an investigation on “Lee Seok-gyu, the spy.”

The CIO discovers that Cha Min-ho and Park Du-sik cases were covered up. Yun-ju approaches Yeon-su, offering to reveal the real culprit of the Kim Tae-yeol case. Yun-ju comes out to meet Yeon-su, and Yeon-su is being followed by multiple parties.

Yeon-su is shocked to find out the truth about Jeong-hyeon. She feels betrayed and is left in agony. When Chung-mo(Lee Seung-joon) finds out about this, he pressures her to step down from directorship. Meanwhile, the CIO staff notice Yeong-geol and Park Won-jong are acting suspiciously. The investigation continues, and Jeong-hyeon encounters Lim Hyeong-rak at Kim Tae-yeol’s memorial ceremony.

Yeon-su acquires the files for “Project Strike Gold”. As she conducts an investigation against Hyeong-rak, she finds out that Park Won-jong has been embezzling funds. Won-jong steals Hyeong-rak’s tablet PC and approaches Yeon-su, asking for her help. Jeong-hyeon tries to protect Yeon-su and now has to beat Yeong-geol in his pursuit of the tablet PC.

Yeon-su finds out Kim Tae-yeol’s real murderer, but Jeong-hyeon is kidnapped by Lim Hyeong-rak. Yeon-su is nervous when she can’t contact him. Later, Jeong-hyeon’s phone and a mysterious dead body are found– what could they indicate? The CIO searches through Hyeong-rak’s hideout. A recording is sent to Yeon-su by someone trying to shake her up. The truth behind the day in 1991 is finally revealed!

Hwang Jeong-ho is declared innocent in his retrial, but Yeon-su is shocked at Kim Tae-yeol’s true form. The determined Yeon-su spurs on his investigation into Hyeong-rak, and tracks his bank account to find that he siphoned off special activity funds. Jeong-hyeon infiltrates the NIS in order to seize the tablet PC that has the crucial evidence needed to arrest Hyeong-rak…!

Hyeong-rak takes Yeon-su hostage and threatens Jeong-hyeon in order to get back his tablet PC. For the wife he protected so dearly, and even for himself, the threat of death draws nearer. Will Jeong-hyeon still be able to live as himself after all of this is over? The final story of a man looking for justice between the truth and the lies.