Glee is finally back next Tuesday (Fox, 8/7c) and to celebrate, TVLine has some scoop straight from the show’s set, where the cast and crew were filming their 300th(!) musical performance Wednesday morning. Read on to find out who’s leaving New Directions, who’s coming back, and what’s in store for the graduating seniors.

THE BIG 300 | So which artist has the honor of being the source for the show’s milestone ditty? Let’s hear it for Adele! Some very lucky reporters were treated to a mash-up of the songstress’ hits “Rumor Has It” and “Someone Like You,” performed by none other than New Directions’ rival McKinley High Glee Club. Mercedes was joined by Sugar, Santana (who can be seen being swayed to the other side in this promo) and most interestingly, Brittany. Hmm, has Brit defected to be with her lady love?

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THE NEW KID | Glee Project winner Damian McGinty (below) seems to be having no problem fitting in with the cast of TV’s hottest show — at least judging from the warm laughs his answers elicited. But his character, foreign exchange student Rory Flanagan, will have a harder time adjusting to his new surroundings when he debuts in next Tuesday’s episode. “He’s having a really tough time fitting in and [he’s] getting bullied a lot,” says McGinty, adding with a laugh, “He’s Irish, thank God! If he was American, this would have been a very short relationship.”

KIDS FROM ‘THE PROJECT’ | Look for Glee Project runner-up Lindsay Pearce to return as Rachel’s rival Harmony in Episode 8, in which “she will be competing against [New Directions],” teases creator Ryan Murphy. Meanwhile, co-winner Samuel Larsen won’t be gracing the show until “around Episode 10 or 11, probably after the Christmas break in January with the new semester,” says Murphy. (In case you missed it, runner-up Alex Newell is going to have “many scenes” with Vocal Adrenaline coach Jonathan Groff. “[Alex] is going to be the love child of Kurt and Mercedes and will turn to them for much advice,” adds Murphy.)

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GRADUATION TIME | “We were talking about doing different things, and we decided to just work on the season,” says Murphy, referring to post-grad plans – including a spinoff – for McKinley’s departing seniors. “Just because they graduate doesn’t mean they’re not on Glee or not a part of the Glee world. [But] we haven’t figured out what that is yet.” He adds that the decision will also depend “on the actors and what their dreams are and what they want to do and what they feel they have left in them.” In the meantime, the show will focus on the core characters and, in case you haven’t noticed so far this season, that means a lot of Broadway numbers. “Because so many kids are graduating this year, I wanted to go back to what the pilot was,” explains Murphy. “If you look at the pilot, it was very Broadway-heavy and classic-heavy. … Creatively, it was a really great decision because it grounded these kids again.”

A TRIBUTE TO… | Although it’s all about character this season, Murphy does admit there’s a tribute episode brewing, one that’s been in the works for two years and will probably air in the spring. Mum’s the word on the artist to be featured, but Murphy did reveal some big names who want to be a part of the show. “I’m having dinner with Barry Manilow, which I’m very excited about,” he says. “Pete Townsend called. He loves the show.”

Gleeks, what are you most excited for? Sound off in the comments!