Captain Sam Vimes' life in the City Watch is changed forever when an impossible figure from his past returns to Ankh-Morpork. 20 years ago, Vimes watched his street brother and gang-leader Carcer Dun fall from a fatal height. Somehow, Carcer is back.

Using the policing know-how of Constable Carrot, the Watch connects Carcer's evil plan to strange goings-on at the magical institution called Unseen University. Perhaps a missing library book has something to do with the dragon attacks in the city.

The Watch must rob the city's most secretive institution in a desperate effort to find the artifact.

Carcer is willing to do anything to find a sword and the Watch is close on his tail.

The Watch must trek through the Unreal Estate to destroy the sword in a magical lake.

In the race against Carcer for the second mystical artifact, Cheery, Angua and Carrot venture into the Mines of Tak. Cheery must confront the darkness in her past. Vimes and Sybil defend the besieged Watch House from Doctor Cruces and her Assassins.

Sam Vimes wakes up with more than the usual hangover. He's slipped into an alternate universe where he's a prisoner in the middle of a jailbreak. In Ankh-Morpork, the alternate-version of Vimes is leading The Watch straight into Carcer's trap.

Carcer's got everything he needs to control the Noble Dragon and destroy Ankh-Morpork. With hysteria on the streets and DEATH preparing himself for a very busy day, can The Watch, this band of misfits, step up and save the city from annihilation?