Choi Jong-hyuk, 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, Jong-hyuk catches a glimpse of the man who kills him before waking up as his 17-year-old self. To prevent his mother's death, Jong-hyuk swears to hunt down the one responsible. Luckily, he has knowledge about the future and his experience as an officer. Will these tools be enough to catch the criminal that eluded him once?