The end of days are upon the X-Men in X-Men: Apocalypse, loosely based on the 1994 comic book series X-Men: Age of Apocalypse. Thing is, unlike most generic sequel tag lines for Hollywood action movies (like “Judgment Day”), “Apocalypse” is an actual mutant — the first mutant ever — who forced mankind to bend to his will by his god-like powers.

In case that’s all sort of confusing, which is fine, because it is, 20th Century Fox today released this clip that explains that plot in the movie so you won’t go in with your head spinning. Starring Rose Byrne (as Moira MacTaggert) with James McAvoy (as Professor Xavier) and Evan Peters (as Quicksilver, not wearing a Pink Floyd shirt), they learn Apocalypse was En Sabah Nur, a Messianic figure who influenced ancient storytellers, like the guys who wrote the Bible. It’s X-Men rewriting scripture for blockbuster and it’s as great as it is totally absurd.

Byrne reprises her role from 2011’s X-Men: First Class as MacTaggert, who in the Marvel comic books is a geneticist, but in these movies she’s a CIA agent and an expert in mutant affairs.

“Ever since the world found out about mutants in ‘73, there have been cults who seen them as some kind of second coming or sign of god,” MacTaggert explains. “I was tracking one of them. They call themselves ‘Ashir En Sabah Nur,’ named after an ancient being they believe to be the world’s first…the world’s first mutant.”

So, not confused about Apocalypse — who will be played by Oscar Isaac — yet? It doesn’t explain why he’s purple, but at least we know he means business.

X-Men: Apocalypse opens May 27.