Min Young moves onto the fifth floor of a new studio apartment with her six-year-old daughter, Joo Hee. She’s concerned when her downstairs neighbor, Han Chang Soo, says that he cannot tolerate the noise above him, even though the two women live tranquility. Furthermore, she is anxious about other residents’ strange behavior. Min Young hardens herself mentally after the move into the new house, largely because of her daughter’s unprecedented odd behavior and continual run-ins with a bizarre woman. Convinced that Joo Hee has fallen sick and perturbed by the mysterious events around the studio apartment, Min Young looks to uncover the truth by herself.