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.