UNSANE "Why yes, my refrigerator is running. Why do you ask?"

The news that Steven Soderbergh filmed Unsane in secret, on an iPhone, feels almost inevitable. The 55-year-old filmmaker has a history of experimenting with technology and messing with viewers’ expectations, and it only takes a few minutes of Unsane to understand why he chose to use the tiny lens of a smartphone to create this taut new thriller.

Soderbergh uses voyeuristic closeups to tell the tale of Sawyer, a lonely, driven young woman with an acidic streak played by The Crown’s Claire Foy. Every detail—Sawyer’s expressive eyes, her freckled skin, the strings of saliva that emerge between her lips in her most emotionally fraught moments—becomes unavoidable and unsettling this close, and so do Sawyer’s actions early on, which seem to indicate either trauma from sexual abuse or other deep-seated psychological issues. That Sawyer’s behavior and history are intertwined only makes her ordeal in Unsane that much harder to untangle.

The victim of a stalker in her former hometown, Sawyer still sees the face of the man who pursued her; wisely seeking counseling, she inadvertently commits herself to a cruelly understaffed mental health institution that takes advantage of insurance loopholes to hold her for seven days. Whether Sawyer deserves to be committed remains a lingering question throughout Unsane, as she violently lashes out at other patients—and a nurse (Joshua Leonard) who may or may not be her stalker.

That’s about as much of the plot as I can recount without revealing spoilers, but even with more details, it’s never quite clear how much we can trust Sawyer. Foy does a remarkable job keeping us focused on her plight, even as she remains an almost entirely unreliable and unlikeable protagonist. While that element of Unsane rubs rough against the film’s subtext of a woman’s voice and story being ignored or doubted, it doesn’t take away from the film’s creeping, fascinating dread.