Mama is an odd mix. At times, it benefits from its lead, played by Oscar nominee Jessica Chastain (Zero Dark Thirty, The Help), being both effective and believable. At other times, unfortunately, the story trips dangerously over itself, creating a tangled mess harder to unravel than the tendrils of the title character’s ever-creeping hair.

A good 45 minutes of the hour and 40 minute film is the set up. Abandoned, two little girls somehow survive in the wilderness for five years. When discovered, Victoria and Lilly are put under the care of their Uncle Lucas, their only surviving family member. The girls have horrid manners, and keep even worse (paranormal) company. Their former caretaker in the woods, aptly named “Mama,” proceeds to haunt Uncle Lucas and his live-in rock-grunge girlfriend Annabel (Chastain).

The meat and bones of the story lies on Chastain’s shoulders, which is quite the task, in that Annabel’s importance doesn’t come into play until nearly too late. There’s something to be said of properly setting up a story, but there also comes a point when the audience feels as if they can’t trust anything presented as being the ‘A’ plot. Fortunately, when the ‘A’ plot is finally reached, the remaining 50 minutes is highly enjoyable, save for an overdone last five minutes.

On top of a dragging first act, plot discrepancies are far too common in Mama. It’s difficult to go in depth with what they are, but let’s just say there are only so many times someone can fully, and quickly, recover from life-threatening injuries. Also, the genesis of how Victoria and Lilly were left abandoned is horribly explained, leaving me questioning the entire movie’s direction.

The film was able to effectively build a slow suspense, and revealed the face of its monster at the perfect point in the arc. It can be appreciated how the film chooses to go on a traditional, safe route for its scares, ie. flickering lights, audio distortion, etc. The scares worked, in that if Mama tried too hard to present new types of frights, the more interesting half of the story of ‘civilizing’ the girls would be detracted from.

This is a fun horror film that benefits from its smart use of safe scares, but is hurt deeply by its at-times unbelievable, unexplained plot. It was neat to see Chastain inhabit a drastically different character than hers in Zero Dark or The Help, but even she couldn’t seem to make sense of the jumpy script.

Grade: B-

Rated: PG-13 (for violence and terror, some disturbing images and thematic elements)

Mama opened in theaters on January 18, 2013.

Photo credit: Universal Pictures