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Will Supergirl cross path again with Superman? After we met young Kal-El a.k.a. the future Man of Steel in Kara's hallucination in the last episode, the CBS series will feature Superman's Fortress of Solitude in an upcoming episode.

First look at Superman's secret place is now revealed via a picture of the 15th episode that will air Monday, February 29 at 8/7c on CBS. According to the official synopsis, Kara travels to Superman's Fortress of Solitude in hopes of learning how to defeat Indigo, a dangerous being who can transport via the Internet and who has a connection to Kara's past. Also, James's relationship with Lucy reaches a crossroads.

Laura Vandervoort, who played Supergirl on The CW's "Smallville", will guest star as the villain, Indigo. She's previously described as "a living, strong-willed supercomputer that was sentenced to Fort Rozz after turning against the people of Krypton."

Superman's Fortress of Solitude has been featured in numerous adaptations of Superman comic books, both in the big screen and small screen. The Fortress of Solitude is typically located in the Arctic, but the comics have also placed the iconic fortress in other locations, including the Antarctic, the Andes and the Amazon rainforest.