Parents beware! Even if your children loved Carla Gugino in Spy Kids, you may not want them to catch her eye-popping role in Center of the World (which opens in select cities Friday before bowing nationwide on May 4). Directed by Wayne Wang, the film offers a shockingly realistic exploration of human sexuality. In fact, World turns heads so well that it's being released unrated to avoid the dreaded NC-17 label. (What's more, the film's racy poster was rejected by several of the nation's top daily newspapers.)

And Ms. Gugino — so wholesome as Spy Kids's comic secret-agent mom — adds spice to the racy mix by playing a hooker. "Playing a prostitute was a departure for me," Gugino tells TV Guide Online. "I did some research — strictly theoretical, of course — to get ready for the part. I find it really interesting to stretch the limits... doing something you've never done before, not knowing if you can really pull it off."

Spy Kids has pulled off a big box-office shocker by coming in at No. 1 for three consecutive weeks. So these days, Gugino — who played the object of Nicolas Cage's obsession in Snake Eyes and was Michael J. Fox's girlfriend during Spin City's first season — is clearly basking in the family film's success. "I'm thrilled to be in it, because I have all these kids in my life," she says. "My boyfriend has two children, my sister has children and I have a godchild. Most of what I've done they haven't been able to see until now. I just love kids, and playing a mom really felt natural to me."

Gugino also confides that it wasn't much of a stretch for sexy co-star Antonio Banderas to play a dad. "Melanie Griffith came to the set with their daughter, and you could just see his face light up," she recalls. "He's an international sex symbol, but he's also funny and goofy and charming. He's just a natural father."