Time travel has become such a staple diet in the world of science fiction that some magazines’ guidelines request people do not send such stories to them.

But in the field of fantasy and under the delightful cover of Terry Pratchett’s Discworld, it is safe to assume that his approach will predictably be slightly unpredictable.

Think of the substandard movie The Butterfly Effect which flitted about so much that it became tiresome and trite. Yet in Night Watch a more linear and measured stance is taken. It’s a clever and subtle idea designed to keep the reader focused on the story not the device.

Vimes, in pursuit of the memorable villain Carcer Dun, is sent back in time due to a magical storm. He’s still in Ankh-Morpork (when it was smaller), but with youthful versions of Vetinari, Dibbler, Nobby, Colon, and of course Vimes himself. What happens when you meet a younger you?

Clearly this has created temporal problems, but the amusing double act of  The Sweeper (Lu-Tze) and Qu step in to help, and put things into perspective:

“I’ve been changing things,” said Vimes.

“… I mean, doesn’t it change history even if you just tread on an ant?”
“For the ant, certainly,” said Qu.

With potential chronological chaos imminent, the time fabric needs repair and Vimes has to deal with the revolution and get his man – Carcer (who also got sent back in time).

Vimes knows about the revolution and other events, because they’ve already happened. Or have they? No need to worry; the author keeps it concise and clear for the reader, and the story moves rapidly and remains entertaining. This isn’t Stephen Hawking’s A Brief History of Time, where people got confused after the first chapter.

Pratchett fleshes out his characters, as always, to perfection. Sir Samuel Vimes is a figure well known to fans and he’s our working class hero . . . with a noble title. He’s the main character throughout and eloquently used as a mouthpiece of the author to jab at the lofty and aloof. Carcer is well played and used sparingly. He knows the limitations of the law and is a thoroughly nasty, but highly intelligent man. Throughout Night Watch readers can also see how their favorites looked thirty years ago.

I could tell you more, but my time’s up.