Mama is, for the most part, a nifty little ghost story that's at times unpredictable and happily, not your average horror flick that's totally dependent on false scares and stops. There are some of those in here, yes, but there's also an emotional undercurrent that's genuinely affecting, until the disappointing and bombastic ending practically ruins it.
It starts out as a unique and chilling mystery, with two little girls whose father (Game of Thrones star Nikolaj Coster-Waldau, who later plays his own twin brother) kills their mother and crashes their car in the woods, hiding them out in a cabin and intending to kill them too until a mysterious entity stops him. Five years later, the girls are found, still young (8 and 5) and nearly feral, having been raised in the wilderness by an invisible being only they can see. Now they're brought back to civilization and taken in by their uncle and his girlfriend Annabel, played by Jessica Chastain, a tattooed and somewhat Goth rocker who doesn't like or want kids in the first place. Of course, their friend "Mama" comes with them, and the spookiness continues in the girls' new domestic setting.
There are further plot complications, as a court appointed psychologist tries to drag the truth out of the older girl, Victoria, but what works best in the movie is Chastain and her evolving relationship with the girls and eventual rivalry with Mama over guardianship of them. Annabel at first comes across as abrupt and nearly mean to these poor kids, but Chastain is such a good actress that she conveys Annabel's changing emotions so clearly and gradually that we believe it as we see it happen, and we start to root for the logical ending, which is for Annabel to save the kids from Mama's firm, ghostly grip on them.
