Jung-Woo, portrayed by Kim Sung-Su, is a neurosurgeon who also engages in bioengineering research. Although he is married, he maintains an affair with Yoo-Gyeong, played by Han Go-Eun, who is a doctor and supports him. One day, Yoo-Gyeong experiences a strange accident that results in her hand being severed. Due to Jung-Woo’s prompt actions, her hand is successfully reattached through surgery. While Yoo-Gyeong’s condition stabilizes post-surgery, she finds herself surrounded by a series of peculiar occurrences.