Two ill-fated men become a comic duo to investigate criminal cases involving a rare brain disease together.

Kim Seo-Jin (Shin Sung-Rok) is a man who is driven only to achieve success in his life. Thanks to his efforts, he is the youngest executive at his company. His life is perfect, with his beautiful violinist wife Kang Hyun-Chae (Nam Gyu-Ri) and a daughter. His wonderful life comes to a halt when his young daughter is kidnapped. He falls deep into despair. To change the past, when his daughter was kidnapped, he contacts Han Ae-Ri (Lee Se-Young) approximately one month in the past. Han Ae-Ri has busy days with her studies and working a part-time job to make enough money to pay for her sick mother's operation. One day, her mother suddenly goes missing. Han Ae-Ri falls into despair, when Kim Seo-Jin from the future contacts her.

A crime action investigation drama about police investigator Jin Kang Ho from the serious crime squad who never gives up on a case until he gets to the end of it. He will solve unsolved cases with a team consisting of a passionate producing director (PD) of an investigative show with low viewership ratings, a detective who used to be a profiler, a bar CEO who puts his violent past behind, and a funeral director who used to be a well-esteemed autopsy doctor at the National Forensic Service (NIS).