Anne, an eleven-year-old orphan, is sent by mistake to live with a lonely, middle-aged brother and sister on a Prince Edward Island farm and proceeds to make an indelible impression on everyone around her.

Who's murdering harmless old men? Who's poisoning the Patrician? As autumn fogs hold Anhk-Morpork in their grip, the City Watch have to track down a murderer who can't be seen. Maybe the golems know something -- but the solemn men of clay, who work all day and night and are never any trouble to anyone, have started to commit suicide....