After dating Ju-won for a year and a half without knowing he was the youngest son of the AL Group family, Yoon-seo decides to break up with him at his mother's request while accepting her money. As promised, she attempts to break up with him by making him gradually resent her. However, she gets drunk and unknowingly calls him to break up.

Now, as the AL CARD's director and Yoon-seo's superior, Ju-won declares war against Yoon-seo in an office he picked right next to hers. He vows he will never let her go and turns up his charms. He attacks her by flirting and clings to her in the most pitiful way. Meanwhile, Yoon-seo succumbs to his request to eat with him 27 times.

Ju-won and Yoon-seo wake up both in despair after realising what they did and said to each other last night, intoxicated. They try to avoid one another at the company but end up face-to-face awkwardly. Meanwhile, Ju-won's mother reminds Yoon-seo of the promise she had made her, and Yoon-seo's brother gets into trouble at school for school bullying.

An unknown number keeps texting Yoon-seo's phone with messages only an ex-boyfriend would text, making her suspect Ju-won. When she confronts him about it, she makes a fool of herself. Meanwhile, the company's new venture in the vacation sector opens a hanok getaway where Yoon-seo's team and Ju-won go for a business trip.

Ju-won leaves his family and shows up at Yoon-seo's door. His appearance exposes their relationship to the team, who even discover that their breakup was because of Ju-won's family's opposition, causing them to create an unbearable atmosphere for her in the office. Meanwhile, a crisis hits the Hanok Stay grand opening art exhibition, but Yoon-seo is away from her desk to handle it.

Yoon-seo struggles to clarify her relationship with Ju Won, even though she knows it's over. Ju-won's lingering feelings make it even harder for her. On top of that, Seong-min unexpectedly enters her life, sparking Ju-won’s jealousy. Feeling overwhelmed, she lashes out at Seong-min’s frivolous words and actions.

While Yoon-seo and Seong-min seem to be getting closer, Ju-won becomes jealous and resorts to Si-won's advice of turning on his belligerent side. His sudden demeanor confuses Yoon-seo and frustrates her, angering her. But when she sees Ju-won with another woman, she is shocked by how flustered it made her.

Ju-won shows up at Yoon-seo's mother's funeral. He's there for her once again, and she cries in his solace. Then, he surprises her with a marriage proposal, leaving her speechless. As he waits anxiously for her answer, circumstances force him to go to Spain, but Yoon-seo rushes to see him at the airport as if she will lose him forever.

Yoon-seo realises that before she can be honest about her relationship with Ju-won, there's something she needs to address first. Aware that the result might not be favourable, she decides to handle the situation on her own without involving Ju-won. Meanwhile, Si-won and Mi-jin are enjoying a wonderful night out together, but what starts as a moment of sincere honesty unexpectedly turns awkward.

While Ju-won and Yoon-seo enjoy the outdoors, the shocking news of Sun-joo's husband's affair in New York spreads. To remedy the shattered image of the company, Sun-joo allows Yoon-seo to marry Ju-won. However, she will expose Yoon-seo's impoverished background to show the humility of the conglomerate family. Ju-won learns about this and then charges to confront his mother angrily, but Yoon-seo stops him.