Steven Soderbergh goes low tech with mixed results. His latest feature, Unsane, is a B-movie horror thriller shot entirely with iPhone cameras. The technical gimmick wears thin as the film's plot unravels. Unsane has a weak script that gives up the goods too soon. The psychological tension is sadly wasted. That's a bummer because British actress Claire Foy delivers a dynamite performance.

Sawyer Valentini (Claire Foy) is a banking analyst adjusting to life in a new city. She has a terse, agitated personality that ruffles her coworkers. Her only friend is her mother (Amy Irving), who worries how she's getting along in her new environment. Sawyer has a strange breakdown. She decides to see a counselor at a local behavioral institution.

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Sawyer feels relieved after her discussion with the therapist. After signing a few papers, she's surprised to be hustled into another room for a medical examination. Her initial relief turns to a nightmare. She has been involuntarily committed. As she struggles to understand what has happened, her worst fears come to light. Her stalker (Joshua Leonard) is somehow employed at the facility. Sawyer is left to wonder whether if she is really insane, or has fallen into a terrifying trap.

Unsane is written by Jonathan Bernstein and James Greer. Their initial concept is quite intriguing. A young woman, who may or may not be crazy, finds herself trapped in an asylum with a predator. There's meat on the bone with this set-up. For whatever reason, Unsane deviates from the mystery elements quickly. We learn in short order whether Sawyer is loony or not. Then the film devolves into rote horror tropes which we've seen a million times before. Soderbergh is rarely predictable. He oddly undercuts the premise of Unsane early, and then spends the rest of the film spoon feeding plot.

Unsane is a murky exercise in guerrilla filmmaking. The actors are shot close-up under low lighting. There are also quite a few scenes with fixed camera points. Soderbergh wants to create an environment of darkness and dread. I felt like I was watching a movie shot by a high school AV club. It's extremely annoying to struggle to see details in frame. It's understood that this is the "look" Soderbergh wanted. I can appreciate low budget filmmaking when it's done well. There's something to be appreciated by a cinematic experience. Unsane is just too unpolished for my taste.

Claire Foy single-handedly props up Unsane. I have never seen her Netflix show The Crown, but have been impressed by her film work. Foy is a bundle of exposed nerves here. Sawyer's struggles are deep and intimate. Soderbergh has her addressing the camera directly in several pivotal scenes. These are the most effective parts of the film. We get a bird's eye view into Sawyer's damaged psyche. Foy continues to be amazing as Unsane derails. I cannot wait to see her as Lisbeth Salander in The Girl in the Spider's Web.

From Bleecker Street, Unsane's initial promise does not deliver. Soderbergh's embrace of different filmmaking techniques is always admirable. He just has to make a film worth seeing in the process. Foy is stellar, but not enough to warrant interest. Going to the movies is expensive these days. I want more bangs for my buck than an exercise with iPhones.

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