Decoy 2023, Ku Do Han, a former lawyer turned detective, is on a quest to uncover the truth behind an unsolved crime from the past. He investigates current cases to piece together clues to find the perpetrator. Along his journey, he encounters Cheon Na Yeon, an eager reporter, and No Sang Cheon, a con artist. Together, they work to unravel the truth and bring justice to the case.