Thunderbirds joins Sgt. Bilko and The Beverly Hillbillies in the ranks of old television programs that never needed to be translated to the big screen. Hardcore fans shouldn't worry about the show's legacy being tarnished, though, because this new Thunderbirds bears only a passing resemblance to the original series. The most obvious change is that the movie has been shot in live-action rather than Supermarionation, the filmmaking process pioneered by "Thunderbirds" creator Gerry Anderson. In the early 1960s, Anderson decided that the world was ready for an all-marionette action-adventure program and created several different shows based around this premise, beginning with "Supercar" and eventually leading up to "Thunderbirds." The sight of those tiny puppets saving the world over and over again proved oddly endearing to audiences at the time, largely because it didn't look like anything else on TV.

It's understandable that a movie studio would opt for real actors over marionettes when adapting the series to the screen. Still, Universal underestimated how central Anderson's Supermarionation process was to the popularity of the series. In fact, seen today, the marionettes are the only things that make "Thunderbirds" worth watching. The show itself is leadenly paced, but Anderson's inventively designed puppets remain fun to watch. Take them away and you're left with a generic kiddie action show, which is basically what the film version becomes. Director Jonathan Frakes throws lots of bright colors and weird gadgets at the audience, but none of this hides the lack of imagination at the movie's center.

The other reason Thunderbirds doesn't feel like an adaptation of the TV show is that the titular heroes actually spend much of the movie offscreen. Instead, the film focuses on Alan Tracy (Brady Corbet), the youngest member of the wealthy Tracy family, who operate in secret as International Rescue, a.k.a. the Thunderbirds. Alan is eager to become part of the team, but his father Jeff (an embarrassed-looking Bill Paxton) doesn't think he's ready. But when the Thunderbirds are trapped onboard a damaged spaceship by an evil criminal known as The Hood (Ben Kingsley, cashing a paycheck), it's up to Alan and his two pre-teen friends, Fermat (Soren Fulton) and Tintin (Vanessa Anne Hudgens), to save the day.

Shifting the focus from the adults to the kids might have worked had the studio hired a better trio of young actors. Unfortunately, they chose three teenagers with a complete lack of charisma; Corbet in particular proves unsuited to the task of carrying a film. You're meant to sympathize with his desire to be recognized by his family, but you'd rather see Paxton send the brat off to his room without dinner.

Like that misbegotten Avengers film a few years back, Thunderbirds always seems vaguely embarrassed by its source material. You get the feeling that the filmmakers would rather be making Spy Kids 4 than a Thunderbirds picture. That said, this movie is nowhere near as unwatchable as The Avengers; every now and then it springs to life with a well-staged bit of action or an amusing line. (Veteran British actor Ron Cook has a lot of fun as a stiff-upper-lip manservant.) Overall, however, it goes through the motions with little enthusiasm. The original "Thunderbirds" has a number of flaws, but you can't say it isn't unique. This Thunderbirds, on the other hand, plays like a second-generation copy of other, better children's films.

-Ethan Alter