You're never sure what the prolific, ever-rebellious Steven Soderbergh is going to do next. But from "Sex, Lies and Videotape" to "Erin Brockovich" to the "Ocean's Eleven" franchise, you know it's going to be different.

His latest, "Unsane," is as peculiar as they come. It is a psycho thriller panic dream that's a galaxy distant from anything he has done over the past three decades. Watching it, I felt that he'd opened Thesaurus.com, looked up "terror" and took a thousand inspirations. This is a relentless anxiety-drencher that is effective to a deeply disturbing degree. It's not just gripping. It's strangulating.

The film follows its ostensible heroine, Sawyer Valentini (Claire Foy), through a mistaken confinement in a psychiatric facility. Foy (Golden Globe and SAG winner as the young Queen Elizabeth II in Netflix's "The Crown") makes the film throb with unease. From the title on, we have valid reason to wonder whether she is delusional in her claims that a longtime stalker has followed her to her new city.

The cinematography is equally dodgy. Soderbergh makes some of his actors look a little fisheye bloated here, a bit off balance there, consistently boxed in by framing that feels claustrophobic. It's out of the ordinary and unsettling, and it perfectly serves the tone of the magnetically creepy story.

To say that Sawyer has some man issues is an understatement. In the first 15 minutes, the financial data specialist is convinced that her boss' invitation to attend a distant business meeting with him is a #MeToo moment in the making. That evening she meets an online date, taking the handsome devil from the bar to her apartment. Once in the dark with him, she freaks out, bolts to her bathroom, medicates herself with prescription pills and lets him find his own way out.

We learn little about Sawyer beyond what she tells us during therapy at a counseling facility: A stalker from her hometown is still after her, she is prepared to defend herself physically, and at one time she considered suicide.

She's held involuntarily at the facility to protect herself and others. Complications ensue, through the uncaring staff and administrators, her paranoid projections or the stalker who has entered the mental hospital. She — and we — are plunged into a complex game of "Who Do You Trust?" Soderbergh could have brought in a leprechaun riding a unicorn and I would have bought it.

The supporting cast gives us Juno Temple as a seedy lunatic totally removed from her recent appearance as a lovely ingénue in Woody Allen's "Wonder Wheel," and "SNL's" Jay Pharoah as an unexpectedly sympathetic opioid addict. They are as surprising as the biblical act of justice connected to one character's crucifix necklace. With a hidden appearance from a famous Hollywood player and a scene that could fit smoothly into Jordan Peele's "Get Out," this horror show keeps the surprises coming.

A daredevil with film tech (and his films' pseudonymous director of photography), Soderbergh filmed the movie in high-quality 4K footage through an iPhone 7 equipped with additional lenses. (Last year he shot his seven-part HBO interactive murder mystery "Mosaic" via smartphone.)

As is often the case with Soderbergh, he makes this odd idea work in unexpected ways. The off-kilter visuals are a crucial ingredient of the elements that make "Unsane" so gaspingly upsetting. I'm not sure whether to recommend it or to warn people away from it. And I say that as a compliment.