There's a manic energy on the set of Glee. It's one week until the show's second season premiere, and the cast and crew have little time to think about how the heavily hyped return will fare.

In the choir room, Amber Riley and Naya Rivera are power-stomping and rump-shaking through another run of Tina Turner's "River Deep, Mountain High." While Eric Stoltz directs the scene from the season's fourth episode, Adam Shankman arrives to prep the fifth. He's shooting segments for Glee's Halloween episode, in which the club mounts a production of The Rocky Horror Picture Show. During a break, choreographer Zach Woodlee shows Shankman some potential moves for "Touch-A, Touch-A, Touch Me," a planned show-stopper for chaste guidance counselor Emma (Jayma Mays).

Off to the side, Chris Colfer is geeking out over the script for the sixth episode, which he just finished reading. "It's so good. Oh, and it's gonna be controversial," says the actor, who was nominated for an Emmy for his portrayal of out-and-proud glee clubber Kurt. "I know we're going to get critics saying the show has gone too gay."

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It's a bit of a three-ring circus, an exercise in stamina for both cast and crew. The overarching goal -- to make the second season sing like the first -- is not, however, lost on anyone. "I think that's the biggest fear, not being able to keep it going," Colfer says. "We've literally come off Everest; it's been such an amazing year. I don't want to say it's downhill from here, but, I don't know!"

Perhaps more than any returning show this fall, Glee has the most to live up to. The musical comedy about the Bad News Bears of show choirs became an instant phenomenon when it launched last year. The show spawned five chart-topping soundtracks, a multi-city concert tour and rapturous attention from the media.

Co-creators and executive producers Ryan Murphy, Brad Falchuk and Ian Brennan have been holed up for weeks writing new episodes, among them, one that celebrates the music of Britney Spears and another that engages in a debate about faith. When they arrive on set for the first time in a long while, the cast giddily welcomes them.

The plan is to take chances, while maintaining the series' potent mix of pop song optimism, snarky comedy and grounded teenage angst. "I almost think it's good that we didn't win the Emmy" for best comedy series, Brennan says. (Glee did win awards for supporting actress Jane Lynch, guest star Neil Patrick Harris, directing and sound mixing.) "This way, we're still reaching."

Glee's second season, which premieres at 8/7c on Fox, even goes as far as to acknowledge its perceived hiccups. McKinley High's roving gossip blogger Jacob lists the offenses: Mr. Schuester (Matthew Morrison) raps too much, Rachel (Lea Michele) is overbearing to the point of grating, New Directions is nothing but "a glorified karaoke club designed to make the inventors of Auto-Tune millions of dollars."

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But like the defiant, showtune-loving Rachel, Glee won't be changing its tune. In fact, the other 38 minutes of the premiere seem to thumb its nose at non-fans, tackling Lady Gaga and Beyonce's Audio-Tune-happy "Telephone" and culminating in a theatrical-yet-plaintive performance of "What I Did For Love" from Broadway's A Chorus Line.

Shankman, a judge on So You Think You Can Dance and the director of the movie-musical Hairspray, calls it a fearless family show, both all-embracing and unafraid to send up sacred cows. "They very successfully push a lot of boundaries," he says. "Rocky Horror, while really risqué, is perfect for Glee because all the kids, in theory, feel like misfits." 

If there's been a consistent criticism about Glee, it's that the show is in danger of overhyping itself through non-stop media coverage and numerous marketing tie-ins, including a clothing line and a series of young adult novels.

"I don't think we shove anything down anyone's throat that they don't ask for," says Rivera, who plays Cheerio Santana. (And it's not the cast leaking news of upcoming guest stars and storylines: All the actors are trained to pre-empt all questions with some version of: "I don't know if I'm allowed to talk about that.")

Heather Morris, who plays Santana's ditzy sidekick Brittany, agrees. "You can feel the difference between this year and last. This year, viewers need to know everything that goes on with the show."

"But it's cool because when we get in here, on set, you can't sense that," Morris continues. "We're in our own Glee bubble."

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The truth is there are no gleeks bigger than those in the cast.

"You guys! Our songs are ringtones!" Michele says, peering into her iPhone. "And you can buy, like, every song we've recorded on iTunes for 80 bucks. It's 100 songs." But what Michele really wants, she's been unable to find. She's been looking online to see if she can download the cast's version of "Empire State of Mind," which kicks off Season 2, and she's irked that it's not available.

Kevin McHale, who plays wheelchair-bound Artie, explains the minor frustration: The studio initially gives the actors only copies of the songs they record, and even then, they don't get everything. "We have to trade," he says. "Like, I'll tell Amber, 'I'll give you 'Safety Dance' for 'The Boy is Mine.' I blast the songs in my car."

Today is an extra good day for the cast, McHale continues, because they're shooting three musical numbers in the choir room, "so we all get to watch. That doesn't always happen."

When the brass section kicks in to the umpteeth take of "River Deep, Mountain High," the actors watching the performance on the monitors go wild as if its the first time they're seeing it. Michele bops her head along, mouthing the lyrics and cheering. Later, after Dianna Agron, who plays Quinn, and Chord Overstreet, who plays new student Sam, perform Colbie Caillat and Jason Mraz's "Lucky," Rivera sighs dreamily. "That was so sweet!"

No one seems to mind the long hours required to learn and record new songs, rehearse choreography, and shoot the show. If they're tired, it's not apparent. "Look at our set. Look at what our workday consists of: singing and dancing," says Cory Monteith, who plays jock-turned-glee clubber Finn. "It kicks ass."

The hard work also comes with a bonus. "Of course, there's pressure on the new season," Monteith says. "But the show requires so much of us that it becomes a wonderful place to hide. It limits our exposure to the hype. I think this whole experience would be a lot more difficult if I had more free time."

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Stoltz, who also directed an episode of Murphy's previous series, Nip/Tuck, has another theory about that. "Remember the Viking ships that would chain the slaves at the bottom to row the galleys? These kids have been chained together for a couple of years and I think they've got Stockholm syndrome. They're in love with their captors."

On the other hand, he also understands them. "We were shooting a mash-up of 'Get Happy' and 'Happy Days Are Here Again,' and I got chills, which is rare for me because I've been around a long time," he says. "But when it does happen, I mean, it's what we live for."