‘Unsane’: On an iPhone, Steven Soderbergh creates effective little thriller

Steven Soderbergh shot the creepy psychological thriller “Unsane” on an iPhone 7 Plus, and while it certainly doesn’t have even a low percentage of the visual richness and vibrant light and fill-the-screen magnificence of high-end Soderbergh films such as “Erin Brockovich,” “Ocean’s Eleven” and “Logan Lucky,” let’s not kid ourselves:

It’s a thousand times better than anything I’ve ever captured with any of these amazing smartphone cameras, and I’ll bet it’s more impressive than anything YOU’VE posted on your Insta Stories.

Eddie Van Halen on a toy guitar is still better than even a talented semi-pro on a top-level Gibson Les Paul. And Steven Soderbergh with an iPhone is still Steven Soderbergh.

(Not that this is the first or most impressive film shot on an iPhone. See Sean Baker’s “Tangerine.”)

So, yes, “Unsane” looks like a real film — albeit a small-budget B-movie with a preponderance of close-ups and some pretty cheesy special effects and flashback sequences.

Technology aside, at the end of the day and the start of the closing credits, the question is: Does the movie work? Does it succeed as a lurid little thriller that cherry-picks elements of vastly superior fare such as “Repulsion,” “One Flew Over the Cuckoo’s Nest,” “Fight Club” and “Misery,” while carving its own twisted path?

Absolutely.

Claire Foy (“The Crown”) delivers a smashing performance as Sawyer Valentini (how’s that for a name!), a smart, beautiful, no-nonsense young professional who has moved some 450 miles and has started a new life in an effort to ditch a longtime stalker.

Joshua Leonard plays the stalker (who may or may not be real). It’s not easy playing the Typical Movie Stalker with the bad glasses and the terrible hair and the awkward and ridiculous fantasies about living happily ever after, but Leonard does a solid job with a standard and somewhat clichéd role.

Even though Sawyer presents a tough exterior, she’s still dealing with the after-effects of that trauma, as evidenced by a Tinder hook-up that suddenly goes sideways, a medicine chest filled with prescribed pills — and Sawyer’s decision to visit a nearby mental health facility to talk to a professional about her situation.

Who can blame Sawyer for dropping in at the Highland Creek Behavioral Center? After all, her insurance covers such a visit, and it seems like a wonderful and welcoming facility. What could possibly go wrong?

After a quick visit with a seemingly sympathetic therapist, Sawyer hastily fills out some “boilerplate” paperwork that gives the facility permission to hold her for 24 hours — and by the time she realizes she’s in trouble and she tries to take back control of her life and get the heck out of there, she’s already in deep, deep trouble.

Turns out that if Sawyer demonstrates she’s a threat to herself or others, they can extend that stay from 24 hours to a week. (Especially since her insurance covers her for at least a week, and let’s just leave it at that.)

So as Sawyer screams and fights and punches and protests, she just makes it worse for herself. And when Sawyer claims a seemingly benign employee is in fact her stalker and has somehow found work at the facility, we begin to wonder if perhaps she truly IS delusional. Maybe she never even had a stalker in the first place?

In a sly bit of casting, the wonderful Amy Irving plays Sawyer’s mother, who springs to action when Sawyer figures out a way to contact her and tell her what’s happening. Who better than a veteran of “Carrie” and “The Fury” to play a protective mom in a 21^st century psychological thriller?

Juno Temple, never one for subtlety, is predictably over the top as a patient who becomes Sawyer’s nemesis. Not a fan of this performance.

On the plus side, former “SNL” cast member Jay Pharoah, best known for his comedy, is rock-solid in a dramatic role as Nate, a patient who takes a liking to Sawyer and risks everything to help her. (We’re almost positive Nate is a good guy. Almost. But Pharoah’s nuanced performance leaves the door just slightly ajar.)

Aimee Mullins is great as Ashley Brighterhouse (another fantastic character name!), the administrator who defends the facility’s practices with unflappable verbal dexterity. My only complaint about her work is we didn’t see enough of it.

In the final act, “Unsane” disappoints with a few easy answers and some predictable resolutions. Why not take the madness to the next level?

Through it all, Claire Foy kills.

In more ways than one.

★★★

Bleecker Street presents a film directed by Steven Soderbergh and written by Jonathan Bernstein and James Greer. Rated R (for disturbing behavior, violence, language, and sex references). Running time: 98 minutes. Opens Friday at local theaters.