Yoon Haneul has always been a pushover, someone who would never say no. Then one day, she opens her eyes and realizes that she has become Aila Mertensia, the antagonist of a novel she had written ten years ago. Haneul is content to live the life of a rich couch potato and binge-read novels. But to her dismay, she soon finds herself stuck in a time loop where her day repeats endlessly, and the only way to escape the loop is to act like Aila Mertensia! Haneul doesn't know the first thing about acting like a villainess. Luckily for her, a mysterious warlock by the name of Killian offers to help her become a true villainess. Her only option is to make a deal with him, but can Haneul really trust this devilishly handsome man?