Scarcely a year on from the events of Guards! Guards!, the Ankh-Morpork City Night Watch find their services are once more needed to tackle a threat to their city. A threat at least as deadly as a 60-foot dragon, but mechanical and heartless to boot. It kills without compunction. It is the first gun on the Discworld.

The original Watch - Captain Vimes, Sergeant Colon, Corporal Carrot and Corporal Nobbs - are joined by some new recruits, selected to reflect the city's ethnic make-up - Lance-Constable Cuddy (a dwarf), Detritus (a troll) and Angua (a w..., well, best to find out for yourself).