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From tearful graduations to massive explosions, fans were left with quite a few unanswered questions as television's most popular shows bid a temporary farewell to their viewers last season.  

To help us understand what we're in for when our favorite series return, Michael Schneider of TV Guide and Matt Mitovich of TVLine.com lend their insider expertise to television's upcoming season.

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While Glee's returning cast post-graduation has been a matter of gossip and speculation for a good, long time, Schneider says we can look forward to an appearance (at the very least) of the entire McKinley High crew in season four. Three notable actors, however, may not make it back in September.

"Even though Ryan Murphy has said pretty much everyone will be back for the new season, the big question marks are Mark Salling, Dianna Agron and Amber Riley, seeing as their characters were in limbo or heading out of town the way things ended," he says. "The plan is now to basically have '2-2-2' shows in one; You've got the characters that have moved onto New York, they're going to a music academy now…[and] we will have the folks back in Ohio dealing with the exit of their friends and moving on with New Directions."

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As for NCIS, the CBS hit signed off for the summer with a bang—literally! A bomb blast ripped through headquarters, possibly killing one (or more) of the all-star cast in the process. Additionally, poor old Ducky's devastating heart attack mid-phone conversation means his return remains an open question mark. Although we'll have to wait a bit to get any real idea of the damage carried over into season 10, Mitovich says the tally of returning characters may have more to do with whether or not the actors decide to renew with the show.

"The big factor going into NCIS's new season is the contracts of the actors who have not signed on to the new season," he explains. "Michael Weatherly, Pauley Perrette, Sean Murray, who played Tony, Abby and McGee, they're still all unsigned, so whether they sign or not could determine whether there characters live or die."

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Watch the video above for more on Glee and NCIS, plus the inside dirt on Revenge and Grey's Anatomy's shocking cliffhangers.