The Adventures of Shark Boy and Lava Girl in 3D

If the title of Robert Rodriguez' new film, The Adventures of Shark Boy and Lava Girl in 3D, sounds like it came from the mind of a 7-year-old, that's because it did. Mr. Rodriguez' son, Racer, gets onscreen credit for the story and screenplay, his apparently fertile imagination inspiring this Spy Kids-Jr. tale of juvenile superheroes.

Max (Cayden Boyd) is a mildly introverted 10-year-old who deals with trouble at home (parents David Arquette and Kristen Davis often argue) and bullies at school by retreating into his own dream world. He keeps a detailed "dream journal" recounting the adventures of the film's title characters.

The movie drops little hints early on that Shark Boy (Taylor Lautner) and Lava Girl (Taylor Dooley) are more real than they seem, and soon Max himself is thrust into an adventure on their home base, Planet Drool, to save his dreams. On Drool, Max battles the alter egos of his teacher, Mr. Electricidad (George Lopez) and his nemesis at school, Linus (Jacob Davich).

The story behind the movie is in some ways better than the finished product. What 7-year-old wouldn't love to have a dad who could bring so vividly to life his imaginary characters and dreams? It's fun to imagine script meetings and character discussions between father and son in their Austin, Texas, home.

But Shark Boy and Lava Girl isn't nearly as well-conceived or constructed as Mr. Rodriguez' Spy Kids trilogy. The story is somewhat haphazard, the characters not as fully developed, and the 3D technology more of a frustration than an enticement.

That said, there are rewards. There's a resolutely personal touch to the film and younger kids will love the wildly free-flowing imagination of father and son, from a banana-split boat floating down a river of milk and cookies to a climactic "brain storm." Parents will also appreciate the film's final message of forgiveness.