Secret

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.

A detective investigates the disappearance of a woman's corpse from a morgue and tries to uncover the cause of her death.

A crooked politician finds himself being accused of murder by a gangster from whom he refused help during a re-election campaign.

Soo-hyun, who has recently moved into a new house, buys a used washing machine through a second-hand app but finds out it doesn’t work. Annoyed by the seller’s irresponsibility, she leaves a comment calling the seller a con man, and reports it to the police. Little does she know that the seller is a psychopathic serial killer who uses an online second-hand market to lure his victims. Her comment renders his hunt for a new victim all but impossible so she becomes his next target. She starts receiving obscene phone calls, countless unwanted food deliveries, and strange men knocking on her door looking for a good time. A trip to the sender’s address proves deadly serious when the police and Soo-hyun find a man’s dead body.