Ian suspects that her older brother's fiancée, who is about to get married, is having an affair with a colleague. To secure physical evidence to stop the marriage within two months, Ian takes an undercover job as a secretary for the CEO of the company where her future sister-in-law works.

Do you think lines exist just so they can be crossed?

The CEO she suddenly finds herself serving, Cha Jeong-han, has a handsome face but a personality to match it poorly, turning Ian's stomach at every turn.

"Yes, lines are meant to be crossed, aren't they?"

Ian, who isn't afraid of being fired, decides to cross the prickly Jeong-han's lines at will. Then, this man, who was so arrogant he didn't know the height of the sky...

Did you put on makeup today?

"Pardon?"

"Because it looks like you’re wearing lipstick."

His attitude suddenly changed?

"I can't do this."

Jeong-han spoke as he overlapped his body against Ian's as if collapsing.

"What can't you do?"

That look you had just a moment ago—I can't show it to anyone else.

Cross the line only with me, you.

A romantic comedy with a precarious, cataclysmic curve!