Hide and Seek

A successful businessman Sung-soo (Son Hyun-joo) receives a phone call that his estranged brother is missing and visits his apartment for the first time in decades to look for him. There, he discovers strange symbols carved into every door and meets Joo-hee, his brother's neighbor. As he delves deeper into the mystery, Sung-soo finds a secret passage connecting his room to another woman's, Eun-Hye, where she was murdered. Ultimately, Sung-soo discovers that Joo-hee is the killer, a deranged kleptomaniac who pretended to be a resident and killed multiple people.