Spoiler alert! We're discussing important plot points and the ending of “The First Omen” (in theaters now), so beware if you haven’t seen it yet.

How does one birth the Antichrist, anyway? The horror prequel “The First Omen” fills in the back story of 1976’s original “Omen" movie, which introduced hell child Damien, though does give him a new family member: a twin sister.

Director/co-writer Arkasha Stevenson’s new “Omen” sets the stage for the original film akin to “Rogue One” leading right into “Star Wars.” While working at a Roman orphanage before becoming a nun circa 1971, American novitiate Margaret (Nell Tiger Free) discovers a heinous conspiracy at play: The youth have ditched the Catholic Church and powerful holy men want to birth the Antichrist as an extreme way to bring believers back. 

“Answering the question, ‘Where did Damien come from?’ gave us a great opportunity to put our imprint on the story, then essentially drop viewers off at the beginning of the ’76 film,” says co-writer Tim Smith.

So, yes, Damien is birthed but here’s what else major happens in “The First Omen,” including setting up for a female-centered sequel.

What happens at the end of ‘The First Omen’?

Margaret protects an orphan named Carlita (Nicole Sorace), who’s believed to be the one being groomed to spawn a devilish kid, but Free’s character makes two important discoveries. They’re both children of Satan – as the church has long been trying to birth a male Antichrist – and, worse for Margaret, she learns she's the one who's been impregnated by the devil, which takes the form of a giant jackal in the wild climactic birthing scene. (That’s a nod to the OG “Omen,” where a jackal’s skeleton is found in the grave of Damien’s mother.)

Margaret gives birth to twins, Damien as well as a newborn girl, and the boy is taken away by church members – and ultimately given to ambassador Robert Thorn (Gregory Peck) in the beginning of the original "Omen." (A picture of Peck in character is seen in passing near the end of the movie.) But Margaret makes it out, too, with Carlita helping her to escape in the prequel's fiery finale.

That scene took four days to film (one of them being Free's birthday), and “I had to kind of just leave my body a little bit,” Free says. “I was having dental surgery the other day and I just had to pretend I was somewhere else, and it was kind of what I had to do there. Because that's exactly what she would be doing in that moment, when you go through something really traumatizing.”

For Stevenson, it’s a moment that ties back to Margaret’s heavenly entrance in the film before her epic descent: In the opening, “she starts coming up the stairs, rising into bold light and everything's beautiful and colorful, and she's just this fresh-faced novitiate. And then at the end is quite literally in hell strapped to a bed getting tortured.”

Is that the most bananas part of the ‘Omen’ prequel?

Surprisingly, no. Stevenson includes a graphic bit early in the movie where a woman gives birth to a demon, with a full-frontal shot of a vagina, and even that is not “the most confronting shot in the movie,” the director admits. Instead, that superlative goes to an homage to the 1981 thriller “Possession,” in which a pregnant Margaret spasms and lets out primal grunts and screams as the thing inside her begins to take over. It’s meant to symbolize “this concept of losing control over your body and your body not belonging to you anymore, and you wanting desperately to grab onto every physical function you have,” Stevenson says.

Her direction to Free for that scene came in a last-minute whisper in the actress’ ear: “Scare the s--- out of them, Nell.” A crew-member friend approached her and "he was like, ‘Ciao, Nell, can I get you a cup of tea?’ He looked at me and went, ‘I’ll come back later,’ ” Free says, laughing. “We had a couple people walk off set while we did it. People were crossing themselves. It was great.”

Does ‘First Omen’ have a post-credit scene?

Nope! However, there is a coda that both ties to the earlier "Omen" films and potentially sets up a future installment: Just before the credits roll, Margaret and Carlita are shown in a remote cabin with the little girl, now seemingly a few years old. Father Brennan shows up at their door, as Margaret greets him with a shotgun, and he comes bearing ominous news about the Antichrist: “They’ve given it a name. Damien.” 

Free calls it “such a cool moment,” and one that opens the door to a sequel featuring the female characters that parallels the Damien movies. “All three of those girls are half jackal: They have the devil in them,” Stevenson adds. “But they've isolated themselves to try and heal from that trauma altogether. So it is really exciting to think about what happens when they emerge from that cabin eventually. I would love to continue exploring that story.”

Her star is also game: “Listen, I love this franchise," Free says. "As long as there's stories to tell in this universe, I'll be there with bells on if they need me.”