Watch Elizabeth is Missing Review: Glenda Jackson Shines in New Mystery Film

Maud (Glenda Jackson) can’t trust her own mind to be honest with her, and its rapid deterioration isn’t just frustrating; it’s downright infuriating.

At first, she’s able to keep her head in one piece by stuffing her pockets with scribbled notes (“Don’t forget to lock up,” “Elizabeth, Salvation Army, 10 o’clock”). Soon enough, though, they become reminders of the fact that she can’t remember much of anything at all. As her dementia worsens, Maud gets lost in the wilds of her memories. Her perspective shifts with such alarming elasticity that it becomes more and more difficult — for her and the viewer both — to understand what’s happening to her and what’s already happened.

“Elizabeth Is Missing,” a bracing movie that aired Jan. 3 in the U.S. on PBS Masterpiece, initially frames itself as a pair of parallel whodunits. In the present day, Maud is trying to track down her friend Elizabeth (Maggie Steed), who seems to have disappeared. At the same time, Maud keeps remembering wisps of long-buried traumas — more specifically, the vanishing of her beloved sister, Sukey (Sophie Rundle), several decades earlier.

Director Aisling Walsh and writer Andrea Gibb work in tandem to create an ever-deepening, empathetic portrait of a woman battling against the quicksand of her brain. In so doing, the film echoes Maud’s experience with her dementia, making viewers question what they’re seeing just as much as Maud does. When it’s confusing (and it often is), there’s never a doubt that the confusion is, in fact, the point. When “Elizabeth Is Missing” ends with a series of stunning revelations, it feels less like a conclusion than a door to new, urgent questions. My first instinct at seeing the end credits was to go right back to the beginning so I might pick up on everything I missed the first time around. It wasn’t lost on me that the film had in essence encouraged me to trace my steps much like Maud has to every moment of every day.

As Maud’s present keeps merging with her painful past, she gets increasingly disoriented, frustrated and determined to push back against any suggestion that she might be too confused to function properly. At a dinner with her daughter Helen (Helen Behan) and granddaughter Katy (Nell Williams), Maud notices that their sympathy is only barely masking a fear of how little control she seems to have over herself, no matter how many brain exercises they do together or friendly signs they stick on every door she might walk through. Sensing the creeping arrival of their pitying condescension, she practically yowls in fury. She plucks at the loosening skin on her hand to confirm she’s still there and unhinges her jaw as far as it will go. “I want to scream, but it’s stuck in here,” she says, pounding at her chest. “All the feelings are stuck in here.”

As Maud, Jackson is tremendous — the walking embodiment of a desperate snarl. For as solid as the film’s production is, it’s hard to imagine “Elizabeth Is Missing” hanging together without an actor as ferociously good as Jackson anchoring it. (In that respect, Liv Hill playing teen Maud also deserves recognition for laying the groundwork for a character who hardens her heart in hopes that it might hurt less when it breaks.) Jackson, now 84, is physically slight but enormously charismatic, with a low rumble of a speaking voice that’s practically a growl. When her mood turns on a dime, as it does in that pivotal dinner scene, the force of it is genuinely shocking.

Watching Maud stalk around town, root up her garden with her bare hands and close her eyes in front of the cold winter ocean, I was somewhat surprised to find myself reminded of Jackson’s recent turn on Broadway as Lear, Shakespeare’s stubborn, doomed king who quickly becomes suspicious of his every waking instinct. Both Lear and Maud — characters joined by pride, separated by circumstance — fight like hell to retain control of their minds. As played by Jackson, their rage at realizing they’re waging losing battles can make them frightening to behold. But Maud, much to her own annoyance, isn’t a king; she’s a woman whose opinion frequently was dismissed well before dementia made dismissing her so easy to do. Getting to see Jackson in this singular twist on a tragic role makes for a deeply affecting experience — and even if you forget the specifics, the crushing sadness of it will linger on.