About the title
Su-hyeon, who has just moved into a new home, buys a washing machine through a secondhand goods app, only to find it doesn't work. Irritated by the seller's irresponsibility, she leaves a comment calling him a scammer and reports it to the police. What Su-hyeon doesn't know is that the seller is a psychopathic serial killer who uses the online secondhand marketplace to lure his victims. Detective Chu is a member of the cybercrime division handling crimes related to buying secondhand goods.