Dr. Jung Se-ok, a once-promising neurosurgeon portrayed by Park Eun-bin. After a catastrophic fallout with her esteemed mentor, Dr. Choi Deok-hee (Sul Kyung-gu), Se-ok's illustrious career plummets, relegating her to the clandestine world of underground surgeries. Operating in secrecy, she grapples with her tarnished reputation while confronting the ethical dilemmas of her new reality.