So-Yeon (Park Min-Young) suffers from claustrophobia due to a traumatic incident that occurred to her as a child. So-Yeon is still treated for her condition to this day. She works as a groomer at a pet shop. One day, a cat named Bidanyi comes into the store. The next day, the owner of Bidanyi is found dead in an elevator. So-Yeon, by request from police officer Joon-Suk (Kim Dong-Wook), takes the cat home. Shortly later, So-Yeon starts to see a mysterious young girl. She becomes more frightened. Then, So-Yeon's good friend Bo-Hee (Shin Da-Eun) is found dead. Near Bo-Hee, there is a cat which Bo-Hee recently adopted from an animal shelter. So-Yeon now fears for her own life. So-Yeon and Joon-Suk investigate deeper into the mysterious case. There is a hidden story related to the cats.
