Choi Jonghyuk, captain of the intellectual crime unit, loses his mother and his own life to a mysterious mastermind for digging too deeply into a case. In his last moments, Jonghyuk catches a glimpse of the man who kills him before waking up as his 17-year-old self. To prevent his mother's death, Jonghyuk swears to hunt down the one responsible. Luckily, he has knowledge about the future and his experience as an officer. But will these tools be enough to catch the criminal that eluded him once?