A man who poured his life savings into a new apartment discovers its walls are full of disturbing noises, hostile neighbors and unsettling secrets.

Korea, 1645 - Joseon Dynasty: a partially blind and gifted acupuncturist, Gyeong-su, is invited to work alongside the royal physician in the palace of King Injo, just before the crown prince Sohyeon returns after having been held captive by the Qing Dynasty. Prince Sohyeon and his father begin to differ in opinion on the future direction of their dynasty, leading King Injo to suffer from severe anxiety and paranoia. One night, Gyeong-su witnesses prince Sohyeon's death. Disbelieved as a witness on account of his blindness, Gyeong-su must struggle to reveal the truth while not falling prey to the power-hungry conspirators of the palace.

Having lost his colleague who was also his brother-in-law to a serial murderer two years ago, homicide detective Jae Hwan is unable to contain his hatred toward the murderer and dives headfirst into hunting the brutal killer. Jae Hwan finally comes face to face with the murderer Jin Hyuk but in the heat of the chase, they get into an accident. Waking up in a hospital, Jae Hwan realizes his body has been switched with that of the murderer. To protect his family and uncover the secret of this body switch, Jae Hwan begins a desperate chase.