Gil Soo-Hyun is exceptionally intelligent. At the age of 10, he went to Harvard University. After he graduated, he decided to work at the FBI and did so for 10 years. Afterward, he decided to go back to South Korea. He now works as the head of the Special Missing Persons Unit. About 1 percent of special missing cases involving violent crimes are handled by the unit. His appearance is almost perfect, but he has a secret. Detective Oh Dae-Young has joined the Special Missing Persons Unit. He has been a detective for 20 years, and he is obsessed with following the law. He is known as a master of finding missing people.