Mama breaks a lot of horror-movie rules, right off the bat.
It gives us an opening with a long back story, and it brings up much more back story as the tale progresses.
It over-explains. It reveals its supernatural menace, not just in glimpses, but full on, and early on. There's never any doubt that this might all be in somebody's head.
But Mama is a reminder that the best chills don't involve chain saws, blood and guts. Horror is a product of empathy — in this case, fearing for the safety of small children and the reluctant twenty-something rocker (Jessica Chastain, transformed with short black hair and Goth makeup) stuck with caring for them.
A prologue tells us of a tragedy. A distraught father (Nikolaj Coster-Waldau) flees financial scandal by shooting people, grabbing his children and fleeing into the snowy mountains of Virginia. They crash, he drags the little girls to a remote cabin, and just as he is about to finish his horror, something happens to him.
Cut to five years later, and searchers finally find the girls. They're feral, non-verbal, skittering around on all fours like rats. The younger of them, Lilly (Isabelle Nélisse), doesn't speak; she gurgles, grunts, eats cherries and sleeps with tree limbs.
Their artist Uncle Lucas (also played by Coster-Waldau) is ready to take them in. His bass-playing girlfriend, Annabel (Chastain), is not.
"Don't call me that," she says with a smile when Victoria (Megan Charpentier) calls her "mom."
"This isn't my job," she tells Lucas.
But thanks to financial arrangements made by the conniving psychotherapist (Daniel Kash) who sees glory in their case, the couple move from Washington to a house in Richmond, Va., and try to bring the girls back into the human race.
Thanks to whatever kept them alive for five years in the woods, that's not going to be easy.
Producer Guillermo del Toro (Pan's Labyrinth) must have had a hand in the production values here, which are state of the art. But what makes Mama work are the performances that co-writer and director Andrés Muschietti gets from the little girls, who are open-faced marvels, conflicted about where their loyalties lie — with the woman who says "Don't call me mom," or with the sinister, mysterious "Mama."
Chastain, far from slumming in a horror film just as she's fighting for that best-actress Oscar for Zero Dark Thirty, adds another gold star to her résumé. Annabel is unhappy, stand-offish and ill-equipped for parenting. Chastain makes her sexy, immature and yet somehow sympathetic.
Horror is all about the short circuit that the screen's technical manipulations — music, editing — cause in our brain, so this isn't high art. But Mama is easily the most moving, most chilling ghost story since 2010's haunted-house tale Insidious, an emotional tale efficiently, and affectingly told.
4 stars out of 5
PG-13 for violence and terror, some disturbing images and thematic elements. Universal. 1:40. Fayette Mall, Hamburg, Movie Tavern, Nicholasville, Richmond, Woodhill.