What happens when a quick encounter with the wrong person puts your engagement at risk?

What happens when a man you had not seen coming suddenly proclaims that you're his fiancé to the world due to a little misunderstanding?

What happens when you realise he was that one kid who swore revenge on you back at high school?

Park Jimin placed it in his heart to one day seek revenge for all those vile things you did to him and nothing will stop him.

Not even that one thing they call love.