Today is the anniversary of the death of Takagi's mentor, Wataru Date. Detective Takagi finishes work early but no one, including Sato, knows where he disappeared to. The Detective Boys are waiting outside the police station for a safety pamphlet photoshoot when a stranger asks them to deliver a parcel to Takagi's girlfriend. The parcel contains a tablet broadcasting a tied up Takagi in real-time. They have about 24 hours to figure out where he is before the bomb explodes. The police investigate the 3 old case files Takagi was recently looking over.
