Those familiar with writer-director-editor Robert Rodriguez's filmography have to hand it to him for comfortably waltzing through just about every genre there is to tackle. He's done westerns (1993's "El Mariachi," 2003's "Once Upon a Time in Mexico"), horror (1996's "From Dusk Till Dawn"), sci-fi (1998's "The Faculty"), comedies (1995's "Four Rooms"), crime noir (2005's "Sin City"), and a family action trilogy (2001's "Spy Kids," 2002's "Spy Kids 2: Island of Lost Dreams" and 2003's "Spy Kids 3-D: Game Over"). Taking a page from the latter "Spy Kids" adventure, "The Adventures of Shark Boy & Lava Girl in 3-D" announces its gimmick right in the title, and it's a gimmick that would have done best to remain in the early-'80s and, possibly, in the IMAX format.

As a would-be wondrous fantasy trip through a young boy's dreams, "The Adventures of Shark Boy & Lava Girl in 3-D" comes equipped with a premise that is limitless in possibilities and imagination. This aimed-for vision starts off promisingly with 8-year-old Max (Cayden Boyd) telling a story to his fourth grade class about his summer vacation, where he met Shark Boy (Taylor Lautner), a boy around his age who was saved from a shipwreck by a community of sharks and has since morphed into a half-human/half-shark species. From there, it is all downhill, and a brunt of the blame needs to go not to Robert Rodriguez's filmmaking, per se, but to his misguided decision to write a screenplay whose story was created by his own 8-year-old son, Racer. While watching something coming from the mind of a child may bewitch the same-aged children in the audience, for just about everybody else its nonsensical plotting will try their patience real quick.

The story, which deals with Max's part-real/part-imagined journey to his endangered dream world where he must find a way to stop the darkness from taking over the land, is a mess. Even within the wide confines of fantasy, it doesn't make much sense, the product of an 8-year-old's confusing mind on a sugar high. Led along by the aforementioned Shark Boy and the literally hot Lava Girl (Taylor Dooley), Max's trip through his subconscious finds a double threat in Mr. Electric (George Lopez), a knockoff of his teacher, Mr. Electricidad, and Minus (Jacob Davich), who is really bully Linus in the real world. The themes on display, most about the frailty of childhood and the importance of never giving up one's dreams, are valid enough, but they self-destruct in a hodgepodge of scenes that barely connect into a cohesive narrative.

"The Adventures of Shark Boy & Lava Girl in 3-D" has a rushed, thrown-together feel to it made all the more glaring by cheesy 3-D (via conventional cardboard glasses) that is ugly and doesn't work in any way, shape or form. It's a shame, too, because the dream world Max enters into, with such places as the Stream of Consciousness, the Land of Milk and Cookies, and a sprawling amusement park, could have been awe-inspiring to look at through simple visual effects work. In 3-D, however, the production values look downright shoddy, with a faded, borderline black-and-white color scheme, and not a single 3-D effect (the kind where things are supposed to jump out of the screen) coming off with success. If one didn't know any better, he or she would assume that this film is a product of 1982 or '83, when "Friday the 13th Part 3-D," "Jaws 3-D" and "Amityville 3-D" were released upon the public. This fad temporarily died off soon after, and for regular multiplex screens, the technology of this format still doesn't work as intended in 2005.

The sort of flash-in-the-pan film doesn't leave much room for performances, and so Rodriguez has elected to cast mostly unknowns in the children's roles. They do their jobs with finesse, but are clearly inexperienced (where's Dakota Fanning when you need her?). The exception is Jacob Davich (2004's "The Aviator"), who brightens up his bully role of Linus/Minus with a charming air of extreme boredom, as if this kid is wise beyond his years in the rules of being bad and is simply going through the motions. By playing the part this way, Davich actually makes his secondary character the most memorable and sharply realized in the whole picture. The adults—David Arquette (2002's "Eight Legged Freaks") and Kristin Davis (TV's "Sex and the City") as Max's bickering parents, and George Lopez (TV's "George Lopez") in the dual role of Mr. Electricidad and Mr. Electric—look more uncomfortable than dedicated, and for understandable reason.

For a family movie intended to have a lot of heart, "The Adventures of Shark Boy & Lava Girl in 3-D" is an emotionally frigid experience. The sentimentality is unconvincing and threadbare—would it have been too difficult for Arquette and Davis to at least appear to be happy at the end?—and the throwaway story does little to satiate its clear ambitions at originality. Furthermore, the useless 3-D never transcends being an archaic stunt, stealing what little involvement there could have been in Max's plight and what visual extravagance it might have held without the damn glasses. "The Adventures of Shark Boy & Lava Girl in 3-D" symbolizes the very nature of a cinematic lost cause.