The Armed Detective Agency receives an anonymous request—and it’s asking for Kyouka’s help by name. But during her investigation with Atsushi, ex-Guild member Montgomery keeps mysteriously getting in their way! And as another old for defies death while seeking a triumphant return, a newer enemy—the sinister Dostoyevsky—bares his fangs against both the Armed Detective Agency and the Port Mafia. As he threatens to slowly but surely swallow the dark underbelly of Yokohama, how will this devil of a man alter the playing field…?