Nothing is more frightening than a ‘time-rich nosy person’. In the movie, Ahn Geo-ul (played by Gyeong Su-jin) embodies this notion perfectly. Her dedication to social justice causes is terrifyingly tenacious. She rents an apartment in the Baek-sae building and soon discovers that there's a loud, hard-to-locate banging noise happening from 4am every night, causing residents to suffer through insomnia. This leads her to decide to disrupt the noise, while also eliminating her eccentric neighbours as suspects. She recruits them to her cause, showcasing her unstoppable force for good. It's also a plea for community cohesion and solidarity.