TO A CHILD this century, Mars Attacks! is an old and quaint movie, thus making some of the films sourced by that 1996 Tim Burton comedy as creaky and ancient as Méliès. The animated Monsters vs. Aliens owes as much to Mars Attacks! as Mars Attacks! owes to Earth vs. the Flying Saucers. The new feature-length animated film Monsters vs. Aliens raids this unkillable era of 1950s science fiction, yet it tiptoes around some of the social questions that used to be debated in those Ike-era watch-the-skies tales.

Susan (voiced by Reese Witherspoon) is a modern Modesto girl of not a lot of character—she's waiting to be married, and that defines her right there. Right before the ceremony she's hit by a meteorite and spontaneously mutates into a 50-foot woman. Drugged and taken away by the Army, she is locked up in a massive steel dungeon with several other monsters: a gelatinous blob called B.O.B. (Seth Rogan); a Creature From the Black Lagoon–style amphibian the Missing Link (Will Arnett); the genetically spliced mutant Dr. Cockroach Ph.D. (Hugh Laurie); and a towering Toho-style bug monster. At first, Susan just wants to get back to her life. Then, when Earth is threatened by an alien conqueror called Gallaxhar (Rainn Wilson), Susan reluctantly accepts her country's call to battle the intruder, under her code name Ginormica.

The monsters have their little routines, but they never seem to evince real personalities—they're too busy being cute. The talkative B.O.B. is basically the same character as Dory in Finding Nemo, and the same shade of blue, too. This story works in some emotional conflict, but as directed by Rob Letterman and Conrad Vernon, it plays about as deep as a Hanna-Barbera backdrop. The political side of the film is uneasy. Kiefer Sutherland plays Gen. W.R. Monger (that name ain't exactly Roald Dahl); Stephen Colbert shows up as a '50s president who can be counted on to make the wrong response. Surely, Colbert should have been doing what he does best: playing a pundit, advising and warning, suavely misinterpreting the situation.

The steel dungeon itself could be a reference to Guantanamo, which, under these circumstances, is like the bite of a dog with rubber teeth. Susan's Keane-painting eyes are enormous even before she becomes a giantess, which gives the film's situation of kidnapping and sequestering a mood that it can't deal with. The movie doesn't really get going until Susan and the team board the evil Gallaxhar's Art Nouveau space ship; and we get some swooping raids on The Wizard of Oz. Gallaxhar has four separate eyes, mostly unsychronized, and a squid body; he has refined aesthetics, like a good villain (his spaceship is mauve inside and partitioned off with frames that look like architect Hector Guimard's cast-iron Paris Metro railings). A giant-robot battle at the Golden Gate Bridge has size but no scope—it's all tangled-up, close-contact wrestling. When Ginormica/Susan skates through the hills of San Francisco with cars for shoes, we do enjoy a true showpiece for the 3-D.

Monsters vs. Aliens is a real technical feat and obviously was damned hard to do, but the film is hampered by the sense of restraint. It doesn't go for the guts (as Disney would have done), for fear of making it too scary for children or too heartfelt for ironic young adults. The Pixar approach would have been to find the passion in the story. Monsters vs. Aliens seems like a producer's passion: a series of story and artistic problems that had to be solved by a team.

MONSTERS VS. ALIENS (PG; 94 min.), directed by Rob Letterman and Conrad Vernon and with the voices of Reese Witherspoon, Seth Rogen and Hugh Laurie, plays valleywide.

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