Joe Jonas and Demi Lovato Joe Jonas and Demi Lovato

Reaching the set of Camp Rock 2: The Final Jam — tucked away in the wilderness about an hour outside of Toronto — requires passing through three separate security checkpoints manned by armed Mounties. It seems a little absurd, right up until a paparazzo darts out of the woods or the unmistakable wail of prowling tween girls pierces the calm. What precious commodity is being guarded behind those roadblocks? The Jonas Brothers and Demi Lovato, at work on the sequel to their megahit Disney Channel movie Camp Rock.

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OMG, indeed. The surprise success of the first film — 10.1 million viewers tuned in to the 2008 premiere — transformed the New Jersey siblings from stars to supernovas and helped Lovato, 18, land the lead in her own Disney series, Sonny With a Chance . "I don't think any of us expected it to do that well," she says.The follow-up, which centers on a clash between the Camp Rock crew and a materialistic new rival camp across the lake called Camp Star — not to mention the swoony romance between Lovato and Joe's characters — is a more elaborate affair, with a larger cast and more complex routines. But will it be able to strike the same chord as its predecessor in this post-Bieber world? "You never know that you have a home run, but between the characters and the songs, it's rock solid," says exec producer Alan Sacks. "Plus, it amazes me how effectively these stars connect with the young audience."And how. Nick

, 17, Joe, 21, and Kevin, 22, have already scored multiple platinum albums, sold out worldwide tours and starred in their own TV series (JONAS L.A.). Still, they seem determined to remain normal — or as close to it as they can get. Off camera, the brothers ride go-karts and play softball. Ask them about each other and the answers line up: Joe is known as the funny one. Kevin, who was the first to shed the purity ring the trio famously wear when he married former hairdresser Danielle Deleasa last December, is "the mayor." Nick is thoughtful, introverted and obsessed with music. ("He's just driven," says Kevin.) They treat Lovato, currently sharing their concert tour bill, like a sister (albeit one whom Joe dated up until recently). Their parents are a constant presence, forever on message about the importance of staying grounded. "I know that not many people get to do this," says Nick. "If you're not wise, it can all go away."Of course, one of the handiest aspects about franchises like High School Musical and Camp Rock is that they not only manage to capitalize on the popularity of their leads (hello, lunch boxes and pillowcases, etc.), but also act as a breeding ground for future marquee names. Camp Rock 2 will give more visibility to supporting players like Alyson Stoner (Caitlyn) and Meaghan Martin (Tess), as well as introduce new blood: Matthew "Mdot" Finley and Chloe Bridges. "The [Camp Rock] family is getting pretty big," says Sacks. "It's about broadening our universe."As long as that ever-expanding universe continues to appeal to young adults, this new age of good, clean (read: chaste) fun will keep on hummin' along. "This phenomenon reminds me of an old-fashioned movie studio where they would have a galaxy of stars working in vehicles in different combinations," says Sacks. For his part, Finley got that first taste of what might be ahead while in Toronto, where he was spotted by some eagle-eyed fans. Afterward, he received counsel from the pros. "I talked to the Jonas Brothers," he recalls. Their advice? "'You'll never quite be used to it. Just be grateful to have people that care.'"Camp Rock 2: The Final Jam premieres Friday at 8/7c on Disney Channel

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