This is the newest Discworld book, and once again we find ourselves in Ankh-Morpork with Sir Samuel Vimes, on the trail of a murderer with the usual set of supporting charactes including the ever-popular Angua, Carrot, Colon and Nobby.

Except, we don't. Fairly quickly, the book takes us (and Vimes) into the past of Ankh-Morpork via a lightning strike on a tower (Back To The Future anyone?) and a magical accident. Vimes quickly realises he has to pretend to be the man that trained him when he first joined up as a guard...and then things start to get confusing.

Firstly, the bad news. It's not as funny as some of the earlier books (for example Guards! Guards!) and many of the characters we know are presented much earlier in their lives. However, that's about it.

The good points are Pratchett's excellent plotting, telling us what's going to happen through the 'memories' of Vimes, yet still making us enjoy how it happens. The impending revolution in Ankh-Morpork is played out realistically, and the emotional pay-off at the end is superbly done. This book, for me, is possibly the best in the series, and reminds me that Pratchett seems to get better the more he writes.

As an aside, the next book is to be called Wee Blue Men and should be out in May.