Oh Ha Na, a hard-working career woman, has been best friends with Choi Won, for seventeen years; when Ha Na gets dumped by her boyfriend on her thirty-fourth birthday for a younger woman, Choi Won exacts revenge.

Ha Na fears the gossip surrounding her that Ho Jun's wedding incited; to make matters worse, things aren't going well at work; her heart oddly flutters because of an intern's kindness.

Ha Na begins to feel attracted to Sung Jae, who intensely approaches her; Won feels uneasy, though he pretends not to care; Ha Na recalls Won's past confession because of Na Young, who reappears single and divorced after several years.

Ha Na wakes up in the same bed as Won, and awkwardness follows when she realizes that she can't stop thinking about it.

Ha Na's ex-boyfriend comes back, and wants to reconnect with her; Won tells So Eun that he is not interested in dating her.

When Seo Hoo learns by chance that So Eun is Won's junior at work, he requests a favor to meet Ha Na; as Won grows anxious, fearing Seo Hoo will hurt Ha Na, he reconsiders his feelings for Ha Na.