First things first: All eight scratch-and-sniff scents on the Aroma-Scope card I was handed at Spy Kids 4D: All the Time in the World smelled like Trix cereal and cardboard.

Maybe I got a dud card, but I definitely got a dud movie to go with it. Nobody expected subtlety from a movie that comes with its own baby-fart smells, but Robert Rodriguez clobbers home his messages about family and quality time with such bludgeoning force that ushers should hand you a helmet to go with your 3-D glasses.

I'm a fan of most of Rodriguez's silly, energetic kids movies (from the original Spy Kids 10 years ago to the underrated Shorts), but this time, he grinds the wacky action and the juvenile and anarchic sight gags to a halt every time he wants to deliver another homily about siblings getting along or parents spending more time with their kids. He needs to get that cookbook that shows you to hide broccoli in your children's mac and cheese.

The film opens with extremely pregnant secret agent Marissa (Jessica Alba) chasing down the mysterious Tick Tock, a criminal who uses time bombs to freeze his would-be captors in their tracks while he eludes them. After she captures him -- and her water breaks -- Marissa leaves the spy game behind to become a full-time mom.

One year later, we see her saddled not only with a food-flinging infant but also with twin stepkids: Cecil (Mason Cook) doesn't make waves, while his sister Rebecca (Rowan Blanchard) misses their late mother and resents Marissa's presence in their lives. Dad Wilbur (Joel McHale) spends most of his time thinking about his Spy Hunter TV show, despite the fact that he's never found one -- and not knowing that he's living with an actual veteran of global espionage.

A villain called the Time Master threatens to speed time ahead to the end of the world, so Marissa is called back into action. Through a series of complications, Cecil and Rebecca wind up on the case as well -- aided by their robot dog Argonaut (voiced by Ricky Gervais, who provides most of the laughs) -- and now-grown onetime Spy Kid Carmen Cortez (Alexa Vega) shows them the ropes, even though she's still nursing a grudge against her fellow operative and little brother Juni (Daryl Sabara).

Longtime fans of the Spy Kids series will enjoy the many nods to past adventures, and this reboot sets us up with a new pair of pint-sized agents. (Rebecca winds up being quick on her feet once she stops being such a brat, and Cecil uses his hearing aids to his advantage, cranking up the volume until he has the ears of a safe-cracker.)

But the tone of Spy Kids 4D: All the Time in the World -- which borrows its subtitle from the theme song to the 007 adventure On Her Majesty's Secret Service -- is all over the place: Alba (who seems to do her best work for Rodriguez) and Jeremy Piven (as Marissa's boss) play the comedy very archly, with tongue firmly in cheek.

Which is fine, except that McHale's trademark deadpan doesn't mesh with the rest of the film at all. It's a clash that pales only to the mix of booger jokes and heartfelt pleas for family togetherness.

And then there's the whole Aroma-Scope gimmick -- I missed the early-'60s phenomena of Glorious Smell-o-Vision! and AromaRama, but when I saw John Waters' Polyester in Odorama, the old shoes and passed gas stickers didn't smell like the air-freshener one. When a poopy diaper smells like candy, it's time to go back to the drawing board, and pretty much everything about Spy Kids 4D demands a do-over before we get a fifth installment.

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