Two cases, two investigators, one location: Japan, Police Headquarters of Prefecture D.

Case 1: Inspector Futawatari is tasked with the personnel restructuring of the prefecture, but the legendary detective Michio Osakabe unexpectedly refuses to retire. Osakabe becomes a grain of sand in the machinery of police bureaucracy—until Futawatari discovers that Osakabe has not stopped investigating a brutal case that was never solved.

Case 2: Department head Tomoko Nanao is notified when a young policewoman suddenly fails to show up for work. Nanao is responsible for all female police officers in the prefecture and has a dark suspicion. When Nanao learns at the women's police dormitory that the missing woman was courted by a mysterious young man, a race against time begins.