Jeffrey Desange (Nikolaj Coster-Waldau) after losing everything in the 2008 stock market crash murders his estranged wife and takes their two young daughters with him. He drives out into the woods where he goes to an abandoned cabin. As he is about to shoot the two daughters and then himself something stops and kills him. Five years pass.
Jeffery’s twin brother Lucas (Nikolaj Coster-Waldau) has been searching for his nieces ever since. A rescue party finds the girls in the cabin. The girls have become feral. They have been under psychiatric care of Dr. Gerald Dreyfuss (Daniel Kash). Dr. Dreyfuss believes that the girls would benefit from a supportive home and agress to let Lucas and his rocker girlfriend Annabel (Jessica Chastain) try and take care of the girls. Victoria (Megan Charpentier) is the oldest and remembers her uncle. Lily (Isabelle Nélisse) is the youngest and is still quite feral.
The children have seem to created an imaginary mother figure while they were in the woods. They call it Mama. And it appears to them as a black moth. Or black moth appears when Mama is close. Annabel doesn’t want to be a mother and she is quite uncomfortable around the children. Lucas is happy that they are home and hopes that they can help the children get better.
Annabelle thinks that someone has been visiting the children in secret. She suspects their maternal aunt who wants custody of the children. One night Annabelle thinks she sees something and Lucas is attacked and knocked into a coma. Annabelle is forced to take care of the children herself.
She talks to Dr. Dreyfuss who original thought that Mama was a personality that Victoria created to help raise Lily. Now he thinks it might have something to do with the death of a mentally disturbed woman who died 100 years ago. He goes to look into the case while Annabelle starts to make a connection with the children much to Victoria’s fear. Victoria knows that it makes Mama unhappy.
Directed by Andy Muschietti and based on his short film of the same name, this is an excellent and creepy horror movie.