Episode 4

With Min Soo's help, Ji Na and Oh Beom are investigating the apartment CCTV and discover a suspicious video. As she turns to the CCTV of Charlie's suspicious behavior in the management office, she encounters friction with the apartment residents who act irrationally. Meanwhile, Hyung Sik is following Woo Hyuk and is shocked to see Woo Hyuk's bizarre behavior. Convinced Woo Hyuk is the culprit who kidnapped Ji Hyeon, Hyung Sik eventually kidnaps him. (Source: Namu Wiki, MyDramaList)