Mama opens with a news report about the economic collapse a few years ago (you can almost hear the filmmakers screaming WE'RE RELEVANT!! from the audience) and a banker type kills his wife and drives his two young (and impossibly cute) daughters to the woods where they stumble on a cabin. The father is about to shoot one of them because, y'know... and an unseen force or entity kills him. Cut to a few years later and the guy's brother Luke is still looking for his nieces. He's dating Annabelle who sneaks in the fact that she doesn't want kids into every sentence. They find the girls in the cabin in the woods and they bring them back to the city be rehabilitated. Luke and Annabelle take them in but this Mama ghost is still following them around, hanging out in the closet, playing with them, giving them a sense of comfort. She's basically a creepy babysitter until the ghost goes all, I won't be ignored and sends Luke into a coma leaving Annabelle to fend for herself.
BIG HUGE MASSIVE SPOILERS AFTER THIS POINT!!
My biggest problem with Mama is why did no one hit her with a bat? Or a chair? Or punch her? It didn't make any goddamn sense. And I kept thinking of this scene.
While I don't advocate physical violence they just needed to explain it. To wit:
LUKE: Why didn't you just hit her in the last scene?
ANNABELLE: It's like a strip club Luke. She can touch us but we can't touch her.
See? Bam! Explained!
Mama is an exercise in waste talented. Director Andres Muschietti creates some really inventive set ups but there's a lot of slack in the film. 80% of it is jump scares, 10% slow moving tracking shots and 10% bat-shit stupid plot. Go back to the original short and save yourself an evening. You can use your newly freed time to see your family, or something.