In Discworld, it’s the night before Hogswatch. You know, that special night when the Hogfather delivers presents to the kiddies. What the Hogfather doesn't realize is that he’s being watched by the Auditors. They are the Discworld’s grey-robed specters who audit not money but the entire universe and maintain the neat order of things. They’ve formulated a plan to destroy human belief so that there's not an atom of it left and the Discworld can finally be theirs.

Lord Downey, the Head of The Assassins’ Guild, is approached with a proposal: enlist the ruthless Mr. Teatime to kill the Hogfather. When the Hogfather disappears, Death is summoned to fill the fat man’s shoes, and a further plan to outwit the Auditors is underway. But who can stop them? Death’s adopted granddaughter and mild-mannered governess Susan Sto-Helit? Mustrum Ridcully, Head of the Unseen University? Ridcully’s motley band of wizards? Hex, the thinking engine?