"Stardust" is an attempted magical fantasy with so much going for it — splashy cast, budget-gobbling digital designs — that you wonder while you watch it why it isn't going anywhere more, well, magical. Based on Neil Gaiman's 1997 comic series, the movie is stuffed with insistent wonders — all manner of witches and spells and general faerie whatnot, plus a sky-borne pirate ship that sails the bounding clouds. But the story sprawls, and it's sometimes confusing (seven scheming princes, with names ranging from Primus to Septimus, are especially hard to keep track of). There are some funny moments, and director Matthew Vaughn, who co-wrote the script, also works up some expensively impressive images. (Although even the best of these, the aerial inventions, were just as enthrallingly approximated in the low-budget "Sky Captain and the World of Tomorrow.") The movie's intended sense of enchantment never rises to the level of real wonder, which leaves it wallowing in the lowlands of whimsy.

The story is set in Olden Times (the late 1830s, in Gaiman's original tale), in the English country village of Wall, so named for the stone barricade that separates it from the magical kingdom of Stormhold next door. A young man named Tristan (Charlie Cox) longs to win the heart of a local beauty named Victoria (Sienna Miller), and as a token of his devotion vows to catch a falling star for her. He boldly crosses the wall into Stormhold to find this item. Meanwhile, far away, the King of Stormhold (Peter O'Toole) is dying, and his sons are contesting with one another to inherit his crown. (Some of them have already been murderously dispatched by their more ruthless siblings, but they hang around as a sort of ghostly black-and-white chorus.) The princes' expiring father decrees that whichever one of them can locate a lost ruby necklace shall be the next monarch, and off they skedaddle in search of it.

Tristan finds the star he needs, but it turns out really to be a beautiful girl named Yvaine (Claire Danes), who's fallen to Earth with the ruby necklace in her possession. Three witches hear about this star girl's arrival, and they determine to capture her and cut out her heart in order to restore their own vanished beauty. One of these cackling hags, Lamia (Michelle Pfeiffer), is selected to undertake the mission and is made temporarily presentable with the remaining shreds of the last heart she and her sisters secured for this purpose long ago. Much chasing, curse-casting and flame-hurling ensues, and then ensues some more. Director Vaughn knows how to keep this cinematic contraption rattling along; getting it to stop, though, was clearly a bit of a problem. (The movie is just over two hours long.)

The actors are generally engaging and seem to be having fun. Michelle Pfeiffer, apparently back to stay after a five-year screen hiatus, brings complete diva authority to her witchy machinations. (Every time she works some magic, she loses a bit of her borrowed beauty. At one point, she casts a spell and her boobs sag.) And Claire Danes, who bears a distracting resemblance to Gwyneth Paltrow here, has a winningly celestial deportment (stressed a little too nudgingly, perhaps, with an overlay of digital glow). Mark Strong brings a dashing caddishness to the role of Prince Septimus, the most dogged of Yvaine's royal pursuers; and Ricky Gervais (of "The Office"), as Ferdy the Fence, dealer in stolen lightning bolts, gathers up his two brief scenes in a big silly beaver hat and walks off with them.

Unfortunately, there are some crucially weak links in the cast, too. Charlie Cox is a suitably handsome lead, but his appeal seems a little too unformed at this point to anchor such a star-crowded picture. Much worse yet, Robert De Niro has taken Gaiman's kindly Captain Alberic, leader of the sky pirates, and turned him, for no reason at all, into "Captain Shakespeare," a mincing transvestite, complete with red boa, petticoats and fluttery fan. This could be the most pointlessly grotesque performance of De Niro's career; it's flabbergastingly unfunny.

In the "Stardust" production notes, the filmmakers blithely cite "The Princess Bride" as a model for their own picture — a ruinous comparison. Not only was that 1987 film incomparable in its limber wit and larky charm, it was also half an hour shorter than this one. In fact, you might want to rent "The Princess Bride" and watch it again. It'll give you something to do in case you're not watching this.

(Watch "Stardust" author Neil Gaiman talk about hanging out on the "Hellboy 2" set, feeling guilty about a flying pirate ship and more.)

("Stardust" is a Paramount Pictures release. Paramount and MTV are both subsidiaries of Viacom.)

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