Celebrity guests are split into two teams to compete in various contests. One guest, known only to himself, is designated the "X-Man", and does his best to cause his team to lose the contests. At the end, all guests try to determine the X-Man's identity.

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.