The children are feral and the aesthetic is creepy, but Mama (which screened after WW press deadlines) probably shouldn't have gotten Guillermo Del Toro's stamp of approval. 

Critic's Grade: C+

The Devil's Backbone
Pan's Labyrinth

The films he's produced, from The Orphanage to Don't Be Afraid of the Dark, are driven entirely by impending doom stalking the young. So it's no surprise that the latest film to get his seal of approval is Mama, a potboiler about feral children stalked by a bloodthirsty apparition. Del Toro flung the film into development based on a single-take freakout of a short by Andrés Muschietti, which was almost like Del Toro fan fiction in its masterfully creepy aesthetic and terrifying titular monster.

Alas, sometimes a short is best left a short, and Muschietti's feature-length take on Mama (written with his sister Barbara) loses its footing at about the halfway point, taking what begins as a spectacularly creepy, minimalist slow-burner and thrusting it into the realm of horror clichés, rife with puzzling character behavior (seriously, dude: You waited until dark to go into the haunted cabin where your bro disappeared) and an even more puzzling insistence on thrusting the ghost at the screen until it's nothing more than an unpleasant secondary character.

But damned if the first hour or so doesn't deliver the chills. The film opens in the middle of the financial crisis, with a deranged father who, having killed several co-workers and his wife, kidnaps his daughters. But he careens off the road and meets an unfortunate fate, leaving his little girls to fend for themselves. Fast forward five years, where we meet the girls' uncle (Nikolaj Coster-Waldau). His exhaustive search for his missing family leads him to discover that little Lily (Isabelle Nélisse) and Victoria (Megan Charpentier) have survived essentially as animals for five years alone, with Lily snarling as she crawls around on all fours.

The film is strongest when it follows the social re-acclimation of the girls and their psychoanalysis, which reveals that they invented an imaginary protector named Mama—only, of course, she's not so imaginary….and isn't too keen that the girls have warmed up to their adoptive mother (a gothed up and surprisingly droll Jessica Chastain). As Mama makes her presence known—announced by fluttering moths and bleeding walls—the film is stomach-churningly tense, with ace sound design hammering every creak of the family's house and guttural. As far as haunted house flicks go, the first hour of Mama is top-tier.

Then people start getting stupid, and the second half of the film teeters into the most macabre episode of Scooby Doo ever, with Chastain essentially going it alone and trying to solve the mystery of why Mama's so incredibly pissed off. It's also at this point that the ghost ceases to be scary. In her early appearances, she's a ghostly shape whose hair and clothing billows as if she's underwater (a nod to Devil's Backbone). Then the film grows impatient with itself, and suddenly Mama's front and center, the entity's herky-jerky movements and air of mystery abandoned for a CGI monster who looks like test footage from The Grudge and seems less interested in terrorizing the characters than popping her head directly into the camera.

Could it be that Mama's real goal is to make the ultimate photo bomb? If so, nicely done. Either way, the over-reliance on special effects and the sacrifice of actual dread earned through organic scares make the film go limp. It initially soars and then lands with a thud, reminding you that despite its imperiled children and creepy aesthetic, a Del Toro film this is not.