Gil Soo-hyun is a genius who entered Harvard University at the age of ten, and graduated with doctorate degrees in math, physics and philosophy. After working for the FBI for a decade, he mysteriously decides to return to Korea, where he gets assigned to lead a a special missing persons task force that goes after the 1% toughest unsolved cases.

He is forced to become partners with Oh Dae-young, a dogged veteran detective with twenty years' experience and a strong sense of justice. Whereas Soo-hyun is overly analytical, Dae-young goes with his gut feeling, and their different approaches causes antagonism.