There is much about Rose Glass’ “Saint Maud” that’s horrifying and unimaginable, so let’s begin with its most poignant, relatable moment: the title character sitting in a bar, alone, just trying to be a person. She nurses a beer and glances around the room; she tries to make connections, trading flirty looks with a handsome young guy, trying to laugh along with a table of contemporaries nearby. None of it takes. Surrounded by people, she feels crushingly alone, and the more she is aware of it, the more she spirals.