One night, Soo Jeong is attacked by an unknown assailant and becomes unconscious but manages to escape the situation thanks to someone. When she comes to she is at a house in an isolated area. The person who saved her is Se Hyeon, a deaf person.
Se Hyeon keeps doing strange things without saying a word. Medical tools can be seen everywhere and CCTV's are installed so every part of the house can be watched. Soo Jeong feels instinctively threatened by him. Just as she is about to get out of the house she finds the final clue regarding her sister's death ten years ago...