Cohen the Barbarian (lately Genghiz Cohen, Emperor of Agatea) and his Silver Horde (they used to be a Golden Horde, but that was before what hair they have left went grey) have set out on one last grand and pointless adventure; Cohen plans to swarm the mountain of the gods and "the last thief will return what the first thief stole".
For those who wonder just what that means, the first thief is currently chained to a mountainside with an eagle tearing at his liver, and Cohen has a large barrel of Agatean Fire Clay...
And, if he succeeds, it's the End Of The World.
And so the Patrician of Ankh-Morpork turns to the wizards of Unseen University and to Leonard of Quirm to figure out how to stop Cohen.
As usual, Leonard has An Idea.
And so Leonard, Captain Carrot of the Watch and Rincewind, the reluctant wizard set out in the Discworld's first spacecraft to orbit the Disc and get there in time to stop Cohen and company.
Unlike the usual Discworld adventure, this is a large-format book with illustrations by Paul Kidby, and the illustrations (while not essential to the story) are hilarious and complement Pratchett's inspired satirical insanity brilliantly.
As usual, though, one can count on Pratchett to hold up a twisted mirror to our own world and to make a few Telling Points here and there.
And -- mirabile dictu! -- Archchancellor Ridcully seems to be beginning to understand some of the implications of quantum theory as it applies to magic and the (more or less) Real World.
Not to mention a kidnapped minstrel to write the saga after it's all over. It is required by The Rules that Heroic Deeds be recounted in sagas.
Usually kept locked up in a tower -- he's a Really Nice Fellow and brilliant painter who can't help inventing things that people with the Wrong Sort Of Minds (most people, actually) see all sorts of potentials for bigger and better mayhem in.
 Recently appointed Chair of Cruel and Unusual Geography at UU, on account of having seen so much of it in a lifetime devoted to hair-raising escapes, Adventures and general Running Away.
An Adventure, properly defined, is someone far away having a truly terrible day.
Not to be confused with the late Josh *Kirby*, who painted the definitive Discworld covers, which we don't get to see in the States.
This fact (and the Generally Awful covers the books *have* had in the States) may be part of the explanation of why the Discworld books don't sell better Over Here...
Probably the best of all of the illustrations is the one printed Very Faintly across a two page spread that is almost invisible -- Kate missed it entirely until i showed t to her -- of Cohen and Blind Offler in the poses of Adam and Jehovah from the Sistine Chapel. Cohen, however, is not limply holding out his hand for the Divine Spark.
And Ponder Stebbins has been promoted from the High Energy Magic department of UU to Head of Inadvisably Applied Magic.