Magical Girl Lyrical Nanoha: The Movie 2nd A's

Months after the Jewel Seed incident, Nanoha Takamachi looks forward to Fate Testarossa’s return from her trial with the Administrative Bureau. Granted conditional clemency for helping avert the earlier crisis, Fate is allowed to attend school alongside Nanoha—but their long-awaited chance at normal days is cut short when a band of shadowy mages attacks without warning. The encounter leaves both girls overwhelmed as their mana is siphoned into a sinister grimoire, and their Devices, Raising Heart and Bardiche, are damaged in the process.

The assailants are the Wolkenritter—Vita, Signum, Shamal, and the familiar Zafila—warriors bound to the Book of Darkness and summoned to fulfill its will. Unaware of the danger tied to the tome is its current owner, the young Hayate Yagami, while the Wolkenritter continue charging the book by forcibly collecting stolen mana, driven by their obligation to see it completed.

With their power drained and their weapons compromised, Nanoha and Fate must regain their strength and stop the Book of Darkness from reaching completion—before its unleashed magic brings catastrophe to the world.