Margaret has a high-powered job in the biotech industry, where she presents Power Point documents on replacement therapy and “cell membrane re-organizing,” a metaphorical career if ever there was one. Everything Margaret does, she does intensely. To say Margaret is an over-protective mother of her 17-year-old daughter Abbie (Grace Kaufman) is to completely understate the situation: Margaret hovers, worries, clings, and Abbie, about to leave for college, feels suffocated. Margaret has a friends-with-benefits situation (sans the “friends” part) with a married co-worker (Michael Esper), and takes a daily run that looks more like a military maneuver than requisite exercise. She runs like she’s chasing someone, she runs like she’s trying to beat the clock. Jim Williams’ urgent score, all chopping alarmist strings, makes every moment into an incipient life-or-death catastrophe, and for Margaret, it is.
At a conference, Margaret gets a side glimpse of a man in attendance. This, we find out, is David (Tim Roth), whom she hasn’t seen in two decades. The film gives no backstory before David arrives (although the clues are there in Margaret’s hyper-vigilant personality), and so all we see is Margaret suddenly fleeing the conference, in a total fight-or-flight panic. She runs all the way home and hides in the bathroom, crooking her elbow over her mouth to muffle her sobs. Eventually, Margaret provides the details in a seven-minute monologue to the hapless young co-worker seen in the cold open. The details are gnarly, to say the least. The relationship between David and the teenage Margaret was bad, sure, but it was bad in a sinister way, something far far out there at the limits of human experience. The word “sadist” may not have applied to the young co-worker’s boyfriend, but it applies to David. (The monologue, and Hall’s performance of it, called to mind Bibi Andersson’s similar monologue about the boys on the beach in “Persona,” not in the particulars, but in its personality-destabilizing revelations. Margaret has never told the story out loud before.)
Margaret fled David soon after they got together, but the damage was more than done. She’s been on the run ever since. Everywhere she goes now, she sees him. She confronts him. It seems, at first, he doesn’t know who she is. But he then cracks a huge smile at her, the smile of a true maniac, and you can see the nastiness underneath, the nastiness tying them together. She tries to file a police report. But there’s nothing to report. He was at a conference, he was sitting in a park. There’s no crime. Margaret doubles-down on her vigilance over Abbie, and begins a stalking campaign. She follows David around, keeping tabs on him. She loses sleep. At one point, after a frightening close-call, she comes home, only to find her breasts have leaked milk through her shirt. Something is happening to her. It’s all out of her control.