Gil Soo-Hyun is extremely intelligent. At the age of 10, he attended Harvard University. After graduating there, he decided to work at the FBI and worked there for 10 years. Afterwards, he decided to come back to South Korea. He now works as the leader of the Special Missing Persons Unit. The unit deals with about 1% of special missing cases involving violent crimes. His appearance borders on perfection, but he holds a secret. Detective Oh Dae-Young joins the Special Missing Persons Unit. He has worked as a detective for 20 years and he has an obsession in observing the law. He is known as a master of missing person cases.