This so-so thriller goes hard with the mature content (language, blood, drinking, sex) but stays rather sedate in the character department, content to keep Spencer's "Ma" at arm's length. Ma is a strange combination: It's like an edgy, misfit Blumhouse (Get Out, Happy Death Day, etc.) production crossed with the work of director Tate Taylor (The Help, Get On Up), who specializes in safe, message-heavy dramas. Spencer won an Oscar for her work in The Help -- and she's an awesome performer in general (see Fruitvale Station, Snowpiercer, Hidden Figures, The Shape of Water, and more). It's puzzling that she would be interested in Sue Ann, other than the chance to have fun going crazy.
Her character's entire psychology is explained by a simple flashback that's interspersed throughout the story but treated so secretively that it feels like it should have built to more. And her final snap feels preposterous, a huge leap of logic. She winds up a monster, rather than pitiable. The teens are likable enough, though Silvers also appears in the much better Booksmart; it's a far smaller role, but it's so much more vivid than what she has here. And, to rub it in, Lewis' character announces in one scene that she's binging a John Hughes marathon on TV, further reminding us that these characters just don't have much inner life. Overall, Ma isn't terrible, but it feels more like those behind it were enjoying "slumming" in the horror genre, without the kind of dedication it takes to make something truly affecting.