Across the globe, a large-scale disaster is taking place. After the arrival of a mysterious fog and the discovery of ability users who appear to have committed suicide, the Armed Detective Agency sets out to investigate these unexplained deaths. The case appears to include an unknown ability user identified as "Collector," a man who may be the mastermind behind the catastrophe. Trust and courage are tested when the Armed Detective Agency forms an odd alliance with the violent Port Mafia in order to defend the city of Yokohama and ability users all over the world from Collector's clutches.