A live-action Terry Pratchett movie is either doomed to fail in every way, or succeed in practically everything.

And "The Colour of Magic," adapted from the first two novels in Pratchett's brilliant Discworld series, is more the former than the latter. This one is no "Hogather" -- it has rather slack direction at times -- but it preserves Pratchett's wry satirical sense of humour. And of course, it's all about a mercenary, cowardly failed wizard.

Rincewind (David Jason) is ejected from the Unseen University, on the very day that Twoflower (Sean Astin) arrives with his many-legged Luggage. He's come to the Disc... to "look at it." But after Rincewind tries to con Twoflower, the Patrician (Jeremy Irons) orders Rincewind to be the guide/bodyguard of the Disc's first ever tourist.

After a massive fire sweeps through the city, the two end up fleeing Ankh-Morpork and running into all sorts of weird things -- a very assertive magic sword, a floating island full of see-through dragons, a dramatic dragonlady in a leather bikini, astrozoologists trying to determine Great A'Tuin's gender, the aged Cohen the (retired) Barbarian, druids, and even getting thrown clear off the Disc in a strange spacecraft. And you thought YOU had problems.

Unfortunately the Unseen University is having troubles of its own -- the magical book Octavo is acting weird, and power-hungry Trymon (Tim Curry) is scheming against the Archchancellor. Even worse, a strange red star has appeared in the sky, and the world is facing destruction. The only thing that can save it is the spell in Rincewind's head.

Perhaps it's because it's based on the first, roughest Discworld books, but "Colour of Magic" is not quite as funny or tightly-written as its predecessor, "Hogather." The writing is not quite as complex or as witty, and the direction sometimes feels a bit slack (such as the bar fight scene, or Trymon skulking and schemind around the University).

But despite these drawbacks, "Colour of Magic" is still a vastly entertaining story -- it has a solid plotline and it chugs away nicely after a somewhat sluggish beginning, and blossoms into full-out complexity about halfway through. Once it gets underway it starts to resemble a road-trip through fantasy-land, with our quirky tourist and wizard bungling their way across the Disc.

Along the way there's some fun action (an upside-down duel), humorous dialogue ("You weren't born with a mysterious birthmark in the shape of a crown, were you?"), and a general air of tongue-in-cheekness. Best of all, it's a fantasy spoof -- Vadim Jean preserves Pratchett's clever satire aimed at the staples of your average fantasy: fantasy babes, prophecies, magic swords, retired barbarians, powerful artifacts, and even the idea of reality warping itself to save the "hero."

Jason is wonderfully snivelly and sour as Rincewind, a failed wizard who basically finds himself repeatedly swept up into bizarre, deadly circumstances even though he didn't want to be involved. Astin is even better as the hilariously oblivious Twoflower, who regards every disaster as yet another great adventure ("We're going to run out of world!" "I have to see that!").

And there's a talented supporting cast -- Curry chews the scenery with sneering aplomb, Karen David plays a humorously over-the-top dragon-lady, and Irons has a small but wonderful role as the chilly, efficient Vetinari. And of course, the brilliant Christopher Lee takes over as an increasingly disappointed Death.

"Colour of Magic" isn't as tightly directed as it could have been, but it still manages to be clever and quite amusing.