Jung-Woo (Kim Sung-Su) is a neurosurgeon and also works in bioengineering research. He is married, but has an ongoing relationship with Yoo-Gyeong (Han Go-Eun). She is a doctor and stands by Jung-Woo. Yoo-Gyeong has a mysterious accident one day and her hand is cut off in the accident. Thanks to Jung-Woo's quick thinking, her hand is reattached successfully with surgery. Yoo-Gyeong's health improves after the surgery, but bizarre events take place around her constantly.

A student becomes a recluse in response to her best friend's suicide and locks herself in her room. She believes that someone is in the room with her. Her alarmed family hires a psychologist to intervene.