The once-peaceful city-state of Lisvalletta has been overrun by a terrible new narcotic known as Anthem. The drug's adverse effects cause the user to go into Overdrive, where they transform into superpowered animals with extraordinary skills. With the police helpless to combat this new menace, the Special Crime Investigation Unit SEVEN-O takes on the duty. To mitigate the hazards of their job, the investigators use the unique "Double Decker" technique, which forces them to operate in "buddy cop" pairs. Kirill Vrubel, an ordinary police officer, dreamt as a youngster about being a hero who would defend his school from a random terrorist assault. When his landlady blackmails him into looking for her, he gets his opportunity to be a hero.