A woman named Go Ae-Rin loses her husband. Along with her neighbour Kim Bon, who is a NIS agent, they discover the truth behind her husband's involvement in a huge conspiracy.
Woo Cheol disappears from the transport van. Bon gets a feeling that he had planned his escape in advance and deducts that he will be trying to flee the country. Tae Yong volunteers to become a bait to catch Yoon Chun Sang and Shim Woo Cheol.
Eun Ha gets attacked at night in King Castle and her flash drive goes missing. Ae Rin finds this incident very suspicious and contacts Ji Yeon at National Intelligence Service. In the meantime, Bon and Yong Tae run into each other, and they plan to find out who The Voice really is. And Yong Tae meets Ae Rin and tells her that Jeong Il's death was an accident.
Young Shil visits King’s Bag, and fortunately, Do Woo and Ji Yeon are not there. She lies to Ae Rin and tells her that she is interested in recruiting her. However, after observing the shop and talking with Ae Rin, she does not have any definite proof that the place is suspicious.
Ji Yeon and Bon try to gather more information about Yoon Chun Sang. They find out Yoon Chun Sang’s house has an extremely tight security system and his butler named An Da Jung is a well-known figure. They plan to infiltrate Yoon Chun Sang’s house through the butler. And Ji Yeon visits Ae Rin to offer a special mission.
Ae Rin finds out that Bon's birthday is coming up. Meanwhile, Sun Mi suspects her husband of having an affair. The KIS conducts an operation to get to the bottom of it.
A month passes after everything's over. Bon leaves for Poland to sort out the unfinished business he has with K. Finally, peace comes to the neighborhood.
Ji Yeon becomes worried, seeing how different Bon has become. While spend-ing time with the housewives, Bon gathers information on the residents of King Castle. A mysterious man orders J International to be cleaned out.
Young Shil finds out that Ae Rin has lied to her about knowing Bon and arrests her under the charges of hiding a wanted criminal. When the director confronts her and asks how she could arrest a civilian, she tells him that Ae Rin has committed a crime. Bon hears about this news and decides to use the DEATH protocol.
Ae Rin and Joon-Joon move into Bon’s house so that Ae Rin can look after him. The four of them have dinner together, and Bon watches them and shows a heartwarming smile. The next day after coming back from grocery shopping, Ae Rin finds out that Bon has left her a note, saying that he will be gone for the time being.
Thanks to Ae Rin, the team gets a camera inside Yoon Chun Sang's house. Bon must get inside the house and retrieve what's hidden in the safe. This is their last chance to wrap up Operation King's Bag.
Ae Rin discovers the secret hideout, and Bon ends up telling Ae Rin the truth. Ae Rin finally understands why strange things have been happening around her. Meanwhile, Yong Tae is onto the people at King's Bag.
Ae Rin passes the interview, but Bon is just worried for her. He starts training her so that she will be able to protect herself from danger. Meanwhile, the neighbors of KIS throws a party to celebrate Bon's return.
After hearing about CornerStone from Tae Yong, Young Shil goes straight to Bon. She says it has to be him that sabotaged Operation Candy three years ago. This only means one thing.
To Bon who is leaving, Ae Rin calls out Wang Jeong Nam, and Bon turns around. Furthermore, Ji Yeon calls Bon on his phone. Ae Rin asks Bon who he truly is and how he knows her boss. Meanwhile, Ji Yeon reminds Bon about the incident in Poland and tells him to end things with Ae Rin.
Wishing to find out more about Ae Rin and her family, Bon volunteers to become a babysitter for Ae Rin's kids. Although Ae Rin isn't aware of his intentions, Bon enters Ae Rin's life. Meanwhile, the man who killed Ae Rin's husband is listening in on every conversation taking place at Ae Rin's house.
A terrorist attack is suspected at a school, and Ae Rin realizes that it is the very school her children are currently at. It turns out that the target is the Minister of Health and Welfare. They try to reach the people who are currently there, but nobody picks up. After hearing about this, Bon rushes to the school.
Yong Tae gets a strange feeling about Bon and decides to look into him. Mean-while, Bon tries to win over Sang Ryeol and turn him into his informant within the KIS. Also, something strange is happening within the NIS.
Bon is chased by Young Shil and her men. Just before he jumps from the bridge to the waters, he is shot in the shoulder. Ae Rin dives in, rescues Bon who is unconscious, and brings him to her place. While she goes out for a short while, Young Shil rings the doorbell.
Ae Rin is abducted and interrogated by her own boss, Yong Tae. He asks her why she went into the place where she was banned from and why she took photos of the bags. However, her explanation makes him dumbfounded. Mean-while, they hear a ruckus outside.
The neighbors at KingCastle Apartment start suspecting that Bon has feelings for Ae Rin. More importantly, they start doubting Bon's identity. Meanwhile, Yong Tae pays a visit to King's Bag.
Ae Rin is fired from her job and desperately looks for another one. Bon tells her to hand in her resume to King’s Bag, his secret office. During the interview, Ae Rin tells Ji Yeon that she has previously worked at J International.
While mourning the passing of her husband, Ae Rin hears that her children went missing. The neighbors hold an emergency meeting to find the missing children. Bon can't help but wonder why the hit man he's after attempted to kidnap Ae Rin's children.
Without letting others know, Bon looks into the real cause of death of Ae Rin's husband. Ae Rin and her friendly neighbors do research of their own. Bon is also busy taking care of the kids while Ae Rin is working.
Bon gets tracked down by his former colleague. While looking after the kids, he tries to lose his tail. While doing so, he finds out that he and his neighbors have been bugged.
Ae Rin is a single mother who starts her day off by cooking and getting her twins ready for school. Her neighbor, Bon, is not entirely comfortable with her hospitality. Meanwhile, Ae Rin gets ready for her job interview.