What is "X-Men: Apocalypse" about?

We know that Oscar Isaac ("Star Wars: The Force Awakens") will be playing the big bad mutant. We know that younger versions of original trilogy characters Storm (Alexandra Shipp), Jean Grey (Sophie Turner) and Cyclops (Tye Sheridan) have been recast. And we know that "Apocalypse" will act as the final chapter in the "First Class" trilogy.

But what has 20th Century Fox and director Bryan Singer made the film about? We didn't know...until now.

"X-Men: Apocalypse" will focus on the emergence of the villainous Apocalypse, possibly the first and most powerful mutant in "X-Men" lore, and his destructive association with Magneto (Michael Fassbender). Professor X (James McAvoy) must gather and train a young group of mutants to combat this new and dangerous foe.

Here's the full and official synopsis:

"Since the dawn of civilization, he was worshiped as a god. Apocalypse, the first and most powerful mutant from Marvel's X-Men universe, amassed the powers of many other mutants, becoming immortal and invincible. Upon awakening after thousands of years, he is disillusioned with the world as he finds it and recruits a team of powerful mutants, including a disheartened Magneto (Michael Fassbender), to cleanse mankind and create a new world order, over which he will reign. As the fate of the Earth hangs in the balance, Raven (Jennifer Lawrence) with the help of Professor X (James McAvoy) must lead a team of young X-Men to stop their greatest nemesis and save mankind from complete destruction."

In addition to Lawrence, Fassbender and McAvoy, returning cast members include Nicholas Hoult ("Mad Max: Fury Road"), Rose Byrne ("Neighbors") and Evan Peters ("American Horror Story"). They will be joined by newcomers Olivia Munn, Ben Hardy and Lana Condor.

Although "Apocalypse" will draw to a close the second "X-Men" trilogy, Fox will give fans a "Deadpool" film and possibly a "Gambit" movie (if they can find a new director soon) in 2016 followed by a final Wolverine solo film with Hugh Jackman in 2017. So there's still plenty of opportunities to get your mutant fix.