People who join abusive cults voluntarily are likely to have preexisting problems. This is makes it harder to disentangle the origins of their symptoms once they leave.
MMMM is a movie about a situation. A young woman (named Martha, renamed Marcy May in the cult she joins, and answering the phone as Marlene, as all the women in the cult do) escapes after two years and moves in with her older sister and her sister's husband. Martha is skittish, weird, paranoid, and somewhat dopey-seeming. As we see flashbacks to her time in the cult, we see how she was manipulated, abused, and finally ended up participating in some of the cult's violence.
It is all well done, I thought. But aside from anatomizing the situation, the movie didn't really go anywhere, and I have a genre desire for imposing plots on inchoate reality. Martha's sister and brother-in-law are on vacation in an isolated lake house, and both are dull and flat of affect. No one ever talks about anything interesting. The cult members are likewise deadpan.
So the movie seems really long. The flashbacks do have a kind of progress to them, but the post-escape scenes do not. The movie does add some ominous touches, as a way of adding suspense, and those are the only trace of narrative energy. Scenes are slow-moving and dull. Maybe the actress who plays Martha, Elizabeth Olsen, acts, maybe she doesn't. I found it hard to be sure.
So: good raw material if you have a project that might include a character who was already damaged and was further damaged by a cult, and who plays a role in an actual plot, but not recommended if you just want to see a movie.