Starring: Matthew Lillard, Sarah Michelle Gellar, Linda Cardellini, Freddie Prinze Jr.,Alicia Silverstone, Peter Boyle,Tim Blake, Nelson, Ruben Studdard ,Seth Green
Director: Raja Gosnell
Producer: Charles Roven ,Richard Suckle

Two years ago, Hanna-Barbera’s cartoon classic was dragged into live-action mediocrity. It was a clever idea that went creatively bankrupt in the production, swapping subversion and verve for dopey cuteness. Save for a nice twist at the end, the first “Scooby-Doo” made the primitive-looking cartoon seem sophisticated.

“Scooby-Doo 2″ is subtitled “Monsters Unleashed,” and the case, if you’re still reading, could hail from any of the old episodes: The Coolsville Criminology Museum’s collection of costumes, once worn by the legendary finks famously nabbed by the kids of Mystery Inc., have been stolen and turned into a pack of monsters. The theft happens right under Mystery Inc.’s nose, and a local reporter (Alicia Silverstone) proceeds to ruin the group’s reputation with her investigative hackwork.

Suddenly, nothing is going right for the gang — not its little detective business and certainly not this movie. Fred (Freddie Prinze Jr.) is dumber than ever. If he’s not secretly reeling over the fact that he and Paris Hilton have the same mangy blond bob, he should be. Screenwriter James Gunn has lifted the veil of sexual ambiguity from Velma (Linda Cardellini) and given her a crush on the museum’s curator (Seth Green). Sarah Michelle Gellar’s Daphne does a lot of ghoul-slaying, but she can’t get a decent line to save a 5-year-old’s life. For example: “Taste the pain, Mr. Glowy Ugly Thing.”

While those three are having their own crises, the royal screw-ups Shaggy (Matthew Lillard) and Scooby (somebody’s hard drive) are looking for redemption. (Wrongly, their blunders are never attributed to drug use.) The duo goes solo, trying to find out who turned the costumes into monsters dripping with ectoplasmic goop. They take so long and are so terrible at it that the people of Coolsville are probably better off calling Ghostbusters.

Before the finale, we get endless slipping and sliding through haunted mansions and dank slums. This is the murkiest kid’s flick in ages, like a theme-park ride through a sewer. The only drops of sunlight come in a slow-motion, Frisbee-tossing flashback to when the gang was young, carefree, and inexplicably played by different actors. For comic high-jinks, the movie puts Shaggy and Scooby in full ’70s regalia. They’re either percussionists from Earth, Wind & Fire or pimps. And for more plot-driven evil, there’s Peter Boyle and Tim Blake Nelson as a pair of wackos.

“Monsters Unleashed” concludes with a double unmasking, during which the culprit half-heartedly says the immortal “Scooby-Doo” clincher: “And I would have gotten away with it if it weren’t for you meddling kids.”