Chrono continues his research on the Book of Darkness. On Christmas Eve, Nanoha and Fate give Hayate a surprise visit, and encounter the Wolkenritter in the hospital room, learning of their connection to her. The groups fight that night on the hospital roof, but two masked men intervene, drain the Wolkenritter's Linker cores and summoning Hayate to the roof while disguised as Nanoha and Fate, and kill Vita in front of her to force her to awaken the Book of Darkness.