In the Season 2 finale of Supergirl, Mon-El and the audience faced the great unknown. The former prince of Daxam was forced to leave Earth when Team Supergirl released lead -- one of the Daxamites' only weaknesses -- into Earth's atmosphere in order to stave off an alien invasion. However, once he hit space, a mysterious portal appeared before him and enveloped his pod. At Comic-Con International in San Diego, several members of the Supergirl cast and crew teased what that means for Mon-El and the Girl of Steel.

"Where Mon-El is and how he comes back is a central mystery of our season," revealed executive producer Jessica Queller.

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"I think [Supergirl] is grappling with that loss as the season begins. In Season 2, she was struggling with 'Can she have it all?' In Season 3, she's really struggling with 'How does she compartmentalize being a superhero with those human feelings that are uncomfortable for her?'" added executive producer Robert Rovner. "So she ends up throwing herself more into work, which complicates all of her relationships."

Chris Wood, who plays Mon-El, was similarly tight-lipped about his character's whereabouts in Season 3. "The bad news is that I can't even say anything about the new season. I don't even have teases for you, which is a bummer for me too, but I can say that when we do find out what happened to Mon-El and where he ends up going and what happens next, I think it's going to be pretty satisfying," he teased. "I think we're exploring some really exciting new areas for the show. I think the fans will be pretty excited."

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Supergirl actress Melissa Benoist also addressed how Mon-El's involuntary departure will impact the Girl of Steel. "I mean, Kara has always been so interesting to me in the trauma that she's experienced," she shared. "Her life has always been a tragedy to me, that was so beautiful that she turned around and was always positive and optimistic. I mean, you lose your entire world and your whole family… unless it's Astra and Non. I don't think she really talks about it. Now, as an adult, it's interesting to see the way she probably handled it when she was a kid first on Earth, and now what she's doing as an adult with this grief."

Returning to The CW on Monday, October 9th at 8 p.m. ET/PT, Supergirl stars Melissa Benoist as the Girl of Steel, David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen, Chyler Leigh as Alex Danvers and Jeremy Jordan as Winn Schott, with appearances by Calista Flockhart as Cat Grant and Tyler Hoechlin as Superman.