Shrek the Third 

• LOST AT SEA: A new director tries to recapture the old magic, but that ship has sailed.

Along time ago in a kingdom called Far Far Away, director Andrew Adamson and a merry band of writers, animators and voice artists created a monster. A franchise that starred a cantankerous green giant turned fairy-tale conventions on their heads and wove whip-smart pop-culture riffs into the cartoon fun - all to the tune of about a billion and a half at the box office, plus 130 million DVDs.

After overseeing the first two installments, Adamson has moved on to another franchise, the Chronicles of Narnia series, and, I regret to report, he's somehow managed to take everything that was magical about these movies with him. Shrek the Third opens with the death of Fiona's frog king father (John Cleese) and spends the next 90 minutes unfolding a CGI fable every bit as lifeless as the croaked potentate.

Mike Myers and Cameron Diaz reprise their roles as the lime-colored newlyweds, of course. Fiona is with ogre, we soon learn, and this has the father-to-be in a state of panic. Compounding Shrek's worries is the fact that he is the apparent heir to the throne, and what he wants more than anything in the world is to return to his beloved swamp and resume his simple way of life. Fortunately for the big guy, it turns out Fiona has a long-lost cousin or half-brother - the connection is never made clear - whose name is Artie (Justin Timberlake) and who is also in line to succeed the king. All Shrek and sidekicks Donkey (Eddie Murphy) and Puss in Boots (Antonio Banderas) have to do is find him and persuade him to take the job.

Finding him proves easy enough. Following a voyage (whose comic high point consists of Shrek accidentally detaching the ship's wheel from the deck due to his brute strength), the trio locates the lad at what appears to be a fairy-tale version of a typical American high school. Sample gags: Jousting bullies belittle less athletically gifted students. Medieval Mean Girls stick their noses in the air and use words such as "like" and "whatever." The anti-drug slogan posted on an assembly-hall banner reads "Just Say Nay."

This, however, is cutting-edge comedy compared with what's happening back in the kingdom. Which, amazingly, turns out to be exactly the same thing that happened in the last film. The superbly coiffed but infinitely dull Prince Charming decides to seize the opportunity of Shrek's absence to take another shot at usurping the throne. We're not expected to notice the recycled plotline, I suppose, because this time he enlists the help of villains from an assortment of stories, including Captain Hook, Rumpelstiltskin, a wicked witch, various evil talking trees, and the Cyclops. Sample witticism (when Cyclops introduces his son): "He has your eye." Who could have seen that one coming?

Meanwhile, back at the castle, a collection of princesses from an assortment of stories (methinks somebody ran out of ideas) await rescue along with Fiona and her mother, the Queen. They include Cinderella, Sleeping Beauty, Snow White and Rapunzel. Near the end of the film, its creators make a half-hearted attempt to defibrillate the flatlined narrative by transforming these women into a Charlie's Angels-style fighting unit that takes on the villain collective. But the returned Shrek and Artie prove the deciding factor in the outcome of the coup. They deliver long-winded speeches designed to convince the fairy-tale bad guys that each has a good guy inside waiting to get out.

By this point I was waiting to get out, too. I loved the first two movies, but Shrek the Third isn't remotely in their league. With former DreamWorks story artist Chris Miller making his debut at the helm, the studio's three-quel is low on energy, short on new ideas, and all but devoid of cheekiness and charm. To make matters duller, the whole shebang's been recalibrated to appeal to very young viewers, leaving parents to chug jumbo vats of java in order to maintain consciousness. If poop, belching, barf and flatulence jokes are your cup of tea, by all means run, don't walk, to the nearest cineplex.

Under any other circumstances, fans of the first two films would be well advised to just say nay.