Before I say anything about “Mama,” all hail Jessica Chastain. The woman has had significant roles in 12 feature films over the last three years, is up for a second Oscar and has been good (and often different) in each part I’ve seen.

Here she’s a black-haired, tattooed bass player in a rock band, who goes from unwilling surrogate mom to fierce protector of two little girls drawn to a malevolent ghost. She turns a simple character into someone about whom we care yet becomes a traditional scream queen when asked to turn up the volume.

You can see why she’d want to play Annabel, who’s funkier and more freewheeling than the buttoned-down or repressed roles she often gets. The film doesn’t solve its big problem – people behave in ways they wouldn’t in life – but Spanish director Andrés Muschietti introduces a rewarding emotional element and ends in a way too daring for American counterparts. (You can also see why Guillermo del Toro, who made the superb “Pan’s Labyrinth,” became executive producer.)

Nikolaj Coster-Waldau (“Game of Thrones”) plays twin brothers: Lukas, Annabel’s artist boyfriend, and Jeffrey, a financier who slays his ex-wife and disappears in the woods with his daughters.

The girls turn up five years later. Eight-year-old Victoria (Megan Charpentier) is verbal and warily affectionate toward Lukas and Annabel; Lily (Isabelle Nélisse), who was an infant when they vanished, remains feral and silent. Both tell a child psychologist (Daniel Kash) they were protected in an empty mountain cabin by Mama. I won’t spoil any surprises, but they’re speaking literally when they say that this jealous, protective specter lives in the walls of any dwelling they inhabit.

Muschietti, who adapted his own 2008 short, wrote the script with sister Barbara (who produced) and Neil Cross. They fill the story with “Oh, puh-leeze” howlers: People insist on examining dark places at night when they could just as easily go in daylight, and Annabel doesn’t seem especially upset by a gaping hole in the wall that oozes black slime, then disappears.

Yet Muschietti does an excellent job of revealing just enough about Mama as we go along (and just enough of Mama herself) to show he’s in control of this genre. Horror movies often have deeper meanings; this could be an allegory about a child torn between her “natural” mother (who has raised her since she can remember) and the stepmother who instills new feelings of love and disloyalty.

Two random thoughts: That haunted cottage is called Helvetia. That’s also the nickname for Switzerland, which is officially the Swiss or Helvetic Confederation. Do the filmmakers hate the Swiss? Are they saying the land of chocolates and secured bank accounts is a horrible place?

And this is the second time in three weeks that I’ve seen Spanish directors pretending they aren’t. Juan Antonio Bayona directed “The Impossible” – where a Spanish family was transformed by the story into Brits – as “J.A. Bayona.” Now Andrés Muschietti is billed in the credits for “Mama” as “Andy Muschietti.”

Does this mean he thinks horror fans don’t want no furriners tryin’ ta shove Euro-scares down our American throats? “Andrés” sounds too exotic, but Andy could pass for a good ol’ American director? I hope not, but I fear so.