When Kim Minjeong starts her surgical career at her dream residency, she does not expect for her ex, Yu Jimin, to be a glorified Cardiothoracic Surgeon, let alone be working in the same hospital as her. With her ex, practically being her boss, Minjeong struggles to keep her emotions at bay as Jimin makes it her mission to be insufferably annoying and desirable, forcing pent up hatred, hidden feelings, and to scratch the surface of their unfinished love story.