Masateru Sara, a detective in the Investigation Division of the Police Agency, lost a junior detective Kota Saito in a line of duty while investigating a murder case, and cheated police staff. Transferred to the Inspector General of Personnel Division 1 to crack down. His past wounds remained unhealed, and his colleagues regarded him as a traitor, leading him to work lonely. Meanwhile, a secret letter arrives at the Personnel Department. It is said that Nako Minaguchi, a former colleague of Sara who belonged to the First Investigation Division, illegally leaked her confidential data. Although Sara is struggling to wash her former companions, his boss Noma orders him to be inspected, and he and Toru Suga, the chief of staff, begin to confirm Minaguchi's actions. Then, the point of contact with an unsolved murder case and the truth of Saito's line of duty death emerge.