Knightley Academy is back in session, and Henry Grim is confident that nothing else can prevent him from earning his knighthood. But Henry and his friends quickly discover that their professors have made some troubling changes to the curriculum--and there's an old classroom filled with forgotten weapons. It is the discovery of this classroom that prompts Henry and Valmont to become the unlikely leaders of a secret battle society. But disaster strikes as Henry, Adam, and Frankie find themselves stuck as Partisan School servants--and something is rotten in Partisan Keep. When Henry is discovered by a secret society of outlaws with a sinister purpose, he must come to terms with a great sacrifice that will take him away from everything he has ever known and wanted.