Several months after Nanoha first became a Magical Girl, she still is unable to personally meet with her new close friend, Fate Testarossa, who is being tried in the Space / Time Administration Bureau for her association in the Lost Logia case. They still communicate through video-mail and hope to see each other in-person once again. Their reunion is not a happy one, unfortunately, as several people who call themselves "Velka-Type Knights" battle Nanoha above the city. Their objective is to fill the pages of the Book of Darkness by stealing the magical power of anyone they can find. Nanoha and Fate must once again team up to stop their plans and save the world.