Night Watch by Terry Pratchett. Published in hardback by Doubleday, £17.99. Out on November 7. Rating *****

ONE of the few novelists whose writing and sense of humour can appeal to both teenage boys and middle-aged women, Terry Pratchett is set for another bestseller place with his latest Discworld novel, the 27th in the world-wide hit series.

Fans of the previous novels won't be disappointed by the latest instalment, Night Watch, another tale of the Ankh-Morpork City Watch, while for newcomers to the series, this story of street urchins, rebels, secret policemen and 'ladies of negotiable affection' is a great introduction to the unique world of the Discworld -- which travels through space on four elephants carried on the back of a turtle. Commander Sam Vimes had it all until a freak weather accident sends him, and Ankh Morpork's most wanted murderer, back into his own past. He has to try to ensure history happens, including orchestrating a rebellion, teaching his younger self how to be a good policeman and dealing with a world changed beyond recognition from his present-day existence. There are cameo appearances from the history monks, first met in the previous novel, as well as younger versions of some of the best-known characters -- with an introduction to the future Patrician Lord Vetinari, the rest of the Watch, including the slightly wet-behind-the-ears young Sam, assassins and seamstresses, Pratchett also creates some memorable new additions. Dark and highly amusing, Night Watch is more proof that Pratchett's genius is still going strong. A guaranteed good read.