Despite the "lukewarm reception" for "X-Men: Apocalypse," it looks like a seventh "X-Men" movie is in the works. Sources say that the upcoming movie about mutants will be titled "X-Men: Supernova."

According to Den of Geek, Production Weekly's note listing included "X-Men: Supernova." The title is listed together with "New Mutants," and it's highly unlikely that they are the same movie. While it's possible that "X-Men: Supernova" is only a working title or codename, it could also be a sign that the X-Men universe is finally venturing into new territory: outer space.

Fans of the X-Men franchise weren't too happy with how 2006's "X-Men: The Last Stand" treated the Dark Phoenix arc, and it is possible that the upcoming film could revisit the same story arc. In the "X-Men: Apocalypse" trailers, Jean Grey (played by Sophie Turner) "was already feeling the early effects of the cosmic Phoenix force."

The Dark Phoenix Saga in the comics portrays Jean passing a point of no return "when she uses a star to recharge her powers." The star, unfortunately, "has inhabited planets in its solar system." Readers can only "imagine what the resulting 'supernova' does."

Screen Rant adds that according to My Entertainment World, "X-Men: Supernova" will "be shooting in Montreal," and that the production start date for the upcoming film is June 15, 2017. The report also included a synopsis of the movie which reads, "Gathered together by Professor Charles Xavier to protect a world that fears and hates them, the X-Men had fought many battles, been on adventures that spanned galaxies, grappled enemies of limitless might, but none of this could prepare them for the most shocking struggle they would ever face. One of their own members, Jean Grey, has gained power beyond all comprehension, and that power has corrupted her absolutely! Now they must decide if the life of the woman they cherish is worth the existence of the entire universe!"

Screen Rant also posits that "X-Men: Supernova" would include a 10-year time jump, putting the film int the 90s, the same time period as the "X-Men: Animated Series." Even director Bryan Singer teased that in the same time frame, it is possible that the gifted mutants have "been to space."

"X-Men: Supernova's" working title was also revealed to be "Teen Spirit," per Production Weekly. The title was chosen to avoid "too much of a furor" during production and is not representative of the movie's plot itself.