Returned from war, Jonathan Strange joins Mr Norrell to try to cure England's mad king, George III, but is frustrated at Norrell's refusal to discuss the magic and legends of old times. Meanwhile, unbeknown tothe magicians, the Gentleman embarks on a scheme to capture Arabella and destroy Jonathan Strange.

Having fled England to Venice, Strange attempts to drive himself insane as a way of gaining access to the fairy magic that he believes can help him resurrect his wife. In so doing, he unleashes a curse that threatens to destroy him utterly.