(18, 102 mins) Starring Cayden Boyd, Taylor Lautner, Taylor Dooley. Directed by Robert Rodriguez.

If You've ever sat and watched a movie and thought to yourself, "wow, a seven-year-old could have come up with this", you're going to have something to say about The Adventures Of Sharkboy And Lavagirl In 3-D.

Because a seven-year-old really did spark the idea for this gaudy family film.

Director Robert Rodriguez's son Racer conjured up the characters and landscapes of the movie while chatting about superheroes.

Unfortunately, Rodriguez (Spy Kids and Sin City) has the kind of pull in the industry to convince the men in suits that a movie thought up by a kid is a viable proposition. More fool them.

The story revolves around a young dreamer called Max (Boyd), who falls into a fantasy world of his own creation where he has to battle the evil Mr Electric Lopez with the help of superheroes Sharkboy (Lautner) and Lavagirl (Dooley).

She emits heat from every pore, he is supposed to be a Tarzan-type who was raised by sharks but is actually a hair-gelled golden boy wearing a silly rubber fin on his back.

There's also a rather obtuse subplot about Max's parents, played by David Arquette and Sex And The City's Kristin Davis, if you can be bothered to sift through the narrative muddle.

Director Rodriguez has made his name for doing everything on his movies and this is no exception, with his name appearing multiple times on the credits. The downside to this, however, is his complete lack of perspective. Aside from the shoddy excuse for a plot, the movie looks terrible, the 3-D barely registers and the acting often errs towards the wooden.

Aimed squarely at children, it alienates both the adult chaperones and is too trite, weedy and vacant for the most forgiving youngsters.