Spoiler alert! The following post discusses important plot points and the ending of “The Exorcist: Believer” (in theaters now), so beware if you haven’t seen it.

Linda Blair returns to the franchise that made her a horror icon in “The Exorcist: Believer,” director David Gordon Green’s direct sequel to the 1973 classic.

The sequel centers on best friends Angela (Lidya Jewett) and Katherine (Olivia O’Neill) venturing into the woods to try and communicate with Angela’s dead mom Sorenne (Tracey Graves). (She succumbed to injuries sustained while pregnant during a Haitian earthquake, though she was able to give birth to Angela). But their mini-seance instead lets in an evil spirit that possesses them both. Angela’s skeptic single dad Victor (Leslie Odom Jr.) reaches out to Chris MacNeil (Ellen Burstyn, reprising her role from the original “Exorcist”) in an effort to help them.

But while Pazuzu is the dark force that inhabited Chris’ daughter Regan (Blair) back in the day, this time it’s the demon goddess Lamashtu. “If I'm following the story of a young woman who's lost her mother, it's a natural fit to find the girlfriend of Pazuzu to have escorted us there,” Green says. Lamashtu is “a demon that could have the insight into some of the horrors that have come before, but also be applicable to a mother that's deceased in childbirth.”

Let’s break down the “Believer” finale, a key cameo and where the new “Exorcist" trilogy goes from here.

What happens in the ending of ‘The Exorcist: Believer’?

Like the original, “Believer” culminates with an exorcism of the two girls. Through them, the demon orders the parents to determine which one lives and which dies. The demonic Angela reveals Victor told doctors to save his pregnant wife over his unborn child 13 years earlier. He refuses to pick between the kids, but Katherine’s father (Norbert Leo Butz) chooses his own child. However, in a twist, the demon kills Katherine and Angela lives.

Was it because the demon tricked them, or the fact that Angela had been blessed in the womb during the Haitian trip where her mom died? Green leaves that up to audience interpretation. “It (messes) with your head the second you make a deal with the devil, and real life has taught us that when you think you've got the choice to make, you're making compromised choices,” the director says.

'It's not cheap scares':How 'The Exorcist: Believer' nods to original, charts new path

What’s the scariest moment in the new ‘Exorcist’?

Fans freaked out by bad things happening to people’s peepers will be unnerved by one scene in particular. When Chris confronts the demonic version of Katherine, the kid taunts her and says that Regan (who hasn’t been in touch with her mom in several years) is burning in hell. Then things get physical, and demon Katherine takes a crucifix that’s fallen from the wall and viciously gouges both Chris’ eyes, blinding her. 

The crucifix is “a very complicated symbol” in the “Exorcist” movies: The most disturbing sequence in the first film is when a possessed Regan stabs herself in the genitals with the holy object. And in "Believer," since Green was setting up a somewhat happy ending (we’ll get to that next), he figured “the devil needs a win in there, too."

'The Exorcist: Believer' review:Sequel is plenty demonic but lacks horror classic's soul

Is Linda Blair in the new 'Exorcist' movie?

Regan is indeed back! In one of the movie’s final scenes, Chris is shown in a hospital room with her eyes bandaged in front of a sunset when she hears the door open. “Victor, is that you?” she asks. And then the camera pans over and Blair’s character appears, holds her mother’s hand and says, “No, Ma, it’s me.”

Blair worked as a behind-the-scenes consultant with the young actresses, but her onscreen return was kept a surprise, even from the vast majority of the crew. “All they knew is there was a character named Bartholomew on the call sheet. We'd flown Linda in kind of under the shadows,” says Green, adding the moment was "incredible" between the two "Exorcist" co-stars. “It was the first time they'd connected in many years and it was real. You look around and the guy holding the boom mic has got like a tear falling out of his eye."

Does 'The Exorcist: Believer' have an end-credits scene?

Nope, but more "Exorcist" is on the way: There are two planned films to follow “Believer,” and Green could bring back Chris and Regan, follow Victor’s family and helpful nurse Ann (Ann Dowd), or maybe even catch up with characters from, say, 1990’s “The Exorcist III.”

But like with his “Halloween” relaunch in 2018, the filmmaker wants to see the audience’s response before finalizing next steps. Even though he has “a roadmap and a lot written,” Green says, “there's always detours and improvisation and ideas and rights and obstacles and things that can get in your way.”