A young lady who has recently moved out on her own claims to the authorities that a user of a second-hand selling app sold her a damaged washing machine, only to discover that he is a psychotic serial murderer.
Kyung-min lives alone in a one-room apartment. One day, she finds traces of a stranger breaking into her room and soon a mysterious murder case begins to unravel.
A tough detective who is part of an elite New York City unit is trying to find out who killed his partner, but uncovers a plot to kidnap mobsters for money.
The story takes place in occupied Korea at the start of the 20th century, where a young student in medicine discovers the murdered body of the son of a government official. Being scared of being accused, he decides to hire Hong Jin-ho (a detective) to help him find the murderer before the police accuse him of the murder.
After people in his town start turning up dead, a grumpy landlord is visited by a man who recounts an unsolved serial murder case from 30 years ago that may hold the clue to what is happening now.