Solving a homicide mystery was never an easy task. Bang Yongguk, a young detective had to experience a dreadful first case where one link connected to another, where domino effect existed. Yongguk placed Kwon Jiyong, a drug dealer, as the prime suspect considering he was one building away from where the homicide occurred. 

The forensics found a bag filled with drug candies in the victim's pocket. Could it be Jiyong was the murderer? Or was he a bait in order to distract the police? 

The mystery couldn't be solved until the missing link was found.