Jonathan Strange accesses ancient and troubling magic as he fights the Napoleonic armies, while Mr Norrell battles to keep his secrets hidden, and the mysterious Gentleman enrols Sir Walter's servant Stephen to help him enchant the beguiling Arabella.

Jonathan Strange's remarkable magic helps England win the Battle of Waterloo, after which Strange returns home hoping for a peaceful new life, but the Gentleman's scheme for revenge wrecks all of his and Arabella's plans, leaving Jonathan Strange a ruined man.