Ma is a strange beast. The film, that is, not the title character portrayed by Octavia Spencer, who imbues her role initially with a matter-of-fact friendliness, and then with an understandable pathos, and finally with round-the-bend vengeance. Okay, so maybe Sue Ann, also known as Ma, is also something of a strange beast. Which makes some kind of cinematic sense, since the film unfolds in the way that many in the horror genre do: with a lead character arriving in a new environment; attractive teens finding themselves in an unexpected situation, and ultimately in danger; and a seemingly malevolent antagonist who means to do them harm. But Ma diverges from many contemporary horror films by eschewing any hint of either the supernatural or a homicidal maniac. The story features no ghosts, no demons, no vampires or werwolves, no mythical or mystical entities, and there’s nary a serial kill in sight. Instead, the film provides a villain with a completely comprehensible justification for her actions—not a reasonable justification, but nevertheless a comprehensible one.

Ma begins slowly, building to a peculiar place, with Sue Ann hosting drinking parties for a group of local high-school students. It is an uncomfortable situation for the audience, and it is clear that something is very wrong. The film reveals Sue Ann’s backstory by degrees, but it’s all pretty clear early on where that part of the tale is headed. What's more surprising is the revelation that Sue Ann has a daughter of her own, and although the film never ends up dealing with it explicitly, it is also obvious that the mother is intentionally harming her child in an example of Munchausen syndrome by proxy.

What is particularly strange, though, is the presence of two Academy Award winners in Octavia Spencer and Allison Janney, an Oscar nominee in Juliette Lewis, and the inclusion of two other well-known actors in Luke Evans and Missi Pyle. Though this is not the type of film that typically attracts famous talent, they all do well in their roles, and Ms. Spencer comes across as completely believable in each part of her performance. Unfortunately, overall, Ma isn’t a particularly good film. It’s not bad, and it’s perhaps better than its contemporaries in the genre, but it is not surprising, does not end satisfyingly, and does not even tie up all of its plot threads. Perhaps better than most horror films, but still a middling effort.