It's been 91 days since Soo Hyeon's wife has passed away. She was raped and killed. Soo Hyun leaves her soul behind the old house and moves to a different apartment, Unit 404. There, he sees another ghost and the strange cohabitation begins.
Soo Hyun notices that the neighbors are acting strange. One of the neighbor dies and Soo Hyun finds out that the girl who used to live in his place dies very similarly with his wife. The neighbors continue to die and Soo Hyun faces a shocking truth during his investigation.
Cast: Park Sung Woong, Yoo In Young, Lee Si Eon, Choo So Young