Growing up as an orphan, Jeong He-Jin didn’t open his heart to anyone. After giving his all to become a cardiothoracic surgeon, he got into an unfortunate accident, after which he woke up not as ‘Jeon He-Jin’ but as ‘Choi GiSeok’. And on top of that, he has to using his skills…? The accident changed his fate drastically… Can he become ‘the Greatest Cardiothoracic Surgeon’ as ‘Choi GiSeok’?