What's Wrong with Secretary Kim - Season 1

Kim Mi-So was exemplary secretary for Lee Young-Joon for 9 years. She put up with everything so she car earn enough money to pay out her family's debt. But now, she wants some time for herself and does not plan to give her life for work, but wants to find a romance with a regular guy. And so, she tells everything that she's quitting work. Lee Young-Joon finds that unacceptable, but hires Kim Ji-Ah as her replacement. During that one month period while Kim Mi-So is training her replacement, Young-Joon decided to put some work into making her stay, even if taht means he has to get involved romantically.

Young-Joon goes to his best friend, Park Yoo-Sik for advice regarding secretary Kim. Kim Ji-Ah starts working at the company as a replacement for Kim Mi-So and co-workers are throwing in a welcome party... to which Young-Joon self-invites to try and get closer to Kim Mi-So. After dinner, they all go to karaoke and drink a bit too much until an incident with Bong Se-Ra happens. Young-Joon plans an extravagant surprise for Kim Mi-So.

After an over the top date, Young-Joon goes for a kiss, but fails. Kim Mi-So goes on a blind date and Young-Joon become jealous. Furthermore, in a competition games, when she teams up with one of the co-workers, Young-Joon goes so jealous he decides to cancel this event in upcoming years. Trying to leave he injures his leg on the stairs. When Kim Mi-So tends to his wound, she notices a scar on his leg just above the ankle. Young-Joon in his jealousy tries to test Kim Mi-So as to how close she would let her co-worker come in order to win the game and they end up dangerously close with her on top of him. On a side note, a mysterious renowned writer of a romantic novels that Kim Mi-So and especially Kim Ji-Ah are fans of is arriving to Korea.

Young-Joon's brother Sung-Yun, who happens to be Morpheus, the renowned writer of romantic novels, returns home. The fight between him and Young-Joon ensues before their mother breaks the conflict. Later that evening Young-Joon visits Kim Mi-So and she tends to his cut lip. While she didn't have time to tidy up her place, she quickly put some of her undergarment under the stuffed bull. As Young-Joon notices the bull upside down and tries to flip it, Mi-So screams and runs to stop him only to end up on top of him on the bed. After the shock subsides she tries to stand but Young-Joon hugs her and pulls her closer.

Kim Mi-So finally finds out that Lee Sung-Yun is Morpheus who she wanted to hire for the promotion event. Young-Joon plans a romantic evening but becomes angry when he realises Mi-So came late because of his brother. Mi-So and Young-Joon almost share a kiss together, but once again he suddenly withdraws and pushes her away.

Young-Joon is trying to apologise for second time failing to kiss her, while Mi-So is becoming conflicting with her feelings for him. Sung-Yun visits the company and everybody is surprised to see the famous Morpheus writer. Young-Joon takes a day to be there for Mi-So and do what she wants for a change. Ji-Ah moves to a new place and realises she has Gwi-Nam for neighbour and that he indeed only has one suit as she suspected all along. He is now determined more than ever to keep an eye on her so she doesn't slip his secret and ruins his image.

Kim Mi-So is determined to find out more about her lost tragic memories of the past, she she asks Park Yoo-Sik if he knows something about Young-Joon's wounds. In the end she ends up believing that Sung-Yun is the boy from her past, more so because he too remembers it. Everybody goes camping on a team building and are surprised to see Young-Joon coming to join them.

Lee Sung-Yun is trying to win Mi-So and during his book promotion event he tells in front of the cameras there is someone he has feelings for. Kim Mi-So was there to witness it, but still goes out after Lee Young-Joon and outright tells him she loves him. He tries to kiss her, but again, is unable to. This time she doesn't see that as a fail, and instead pulls herself closer and she kisses him.

Young-Joon is so happy that Kim Mi-So is now his girlfriend, he does not shy from showing that to anyone, and even going as far as doing some of her secretarial things instead asking her for it, which makes people at work puzzled. Park Yoo-Sik is rattled when he sees his ex-wife crossing the street with another guy in a friendly manner, for whom he assumes to be her new boyfriend or a lover. Ji-Ah and Gwi-Nam are becoming more friendly. Young-Joon hides in a closet when Mi-So's sisters come to visit her. Mi-So definitively tells Sung-Yun she's not interested in him, and also starts suspecting that Young-Joon may be the boy from her past after talking to his mother.

Kim Mi-So further suspects that Young-Joon is boy from her past and becomes certain when she recognizes him on his young photo. Just to be sure, she asks Lee Sung-Yun to tell her which of the boys on the photo is him, to which he too is surprised because he thinks she remembers him and because he still believes he was the kidnapped boy and not his brother. Guys at work decide to have welcome party at Kim Ji-Ah's new place, and things become hectic when both Ji-Ah and Gwi-Nam try to hide him. Young-Joon goes to an annual special day that Mi-So hangs out with her sisters. His goal is to make them like him and to show them he is serious about Kim Mi-So. Sung-Yun is devastated after finding out he had wrong memories. Mi-So has a flashback while watching magic art and just before passing out realizes she remembers everything.

Kim Mi-So lost consciousness as she remembers everything. During her recovery, we see what really happened in the past and also when Young-Joon first saw her after all that time and how long he waited for her to recognise him. Him Mi-So is devastated by what Young-Joon had to go through by himself, remembering everything all the time. Young-Joon tries to force Mi-So to rest, but she returns to her work the next day. So he send the entire team to a spa under pretense of doing it as part of work. Park Yoo-Sik meets his ex-wife at a restaurant where they went for her birthday and runs into her with a guy. He realizes he was her cousin, but only after venting out and accusing her about dating someone new so soon. Young-Joon tells Mi-So to come to his place as he is worried about her regaining memories for his has first-hand experience how painful that was. She refuses, so he appears on her doorstep and tells her if she won't come to his place, he'll be staying at hers.

Young-Joon stays at Mi-So's place, but Kim Mi-So can't seem to relax with him in bed so she's trying to do all other things instead. Eventually, they decide to go to his place because it's much bigger and has multiple rooms. But Young-Joon is still worried and decides to stay next to her and ends up singing her a lullaby. To return the favour for a good-night sleep, she decides to make him a breakfast. More is revealed about Young-Joon past after the incident.

Young-Joon and Mi-So were preparing for a night together, but were abruptly interrupted by the problems at work. By the time the problem was solved, Mi-So already fell asleep and any attempt by Young-Joon to wake her up failed. Young-Joon had to go to business trip for a whole week and that will just add up to them missing each other. Go Gwi-Nam gets promoted and joins the rest of the team on the same floor. Mi-So's father ends up hospitalized and she spends some time taking care of him.

Everybody finds out about Young-Joon and Mi-So being in a relationship. Young-Joon tried to impress Mi-So's father.

Kim Mi-So's father accepts Young-Joon and they both get drunk. Mi-So decides that she likes her work and she announces she will not be quitting. Young-Joon proposes Mi-So and this time she says yes.

Young Joon and Mi So finally get married.