Steven Soderbergh’s return to feature filmmaking after a brief “retirement” resulted in the delicious heist comedy “Logan Lucky” last year, and now brings “Unsane,” a grubby psychothriller whose ultimate claim to fame might be that it was shot entirely on a smartphone (wielded by the director himself under his usual nom de camera Peter Andrews). While as a technical feat that might be interesting, though hardly new (remember “Tangerine”), it doesn’t ensure that the movie will be particularly good, or memorable.

And “Unsane” isn’t. In spite of its innovative shooting technique, it’s actually a throwback to “women in peril” movies from the forties, fifties and sixties, very often pure exploitation pieces, but with a modern twist that plays into modern fears about medicine as a racket. That gives it a thematic connection to Soderbergh’s far more effective “Side Effects,” which played on contemporary suspicions about big pharma and the physicians who sell their souls to it.

In this case the villainy is perpetrated by a facility that’s part of a profit-making chain of sympathetic-sounding “behavioral centers” that are supposedly devoted to helping folks with psychological problems but are actually more interested in conning them into committing themselves for treatment until their insurance runs out. The unhappy patient is Sawyer Valentini (Claire Foy), a smart financial analyst who has relocated from Boston to Pennsylvania to escape the attention of a stalker named David Strine. His persistent harassment had led Sawyer to consult a protection specialist (played by a star who’s worked with the director before but appears here unbilled); his advice is so thorough that she decides simply to flee instead.

Unfortunately, after thinking she’s seen David at her office, but being uncertain about whether she’s merely hallucinating, Sawyer decides to consult a therapist (Myra Lucretia Taylor) at the Highland Creek Center, who uses her admission that she’s occasionally thought of suicide as a rationale for having her sign what she describes as “boilerplate” forms that actually include a self-commitment provision. After she’s summarily taken into a psychiatric ward for twenty-four hour observation, her behavior—which includes lashing out at a hostile roommate, Violet (Juno Temple), and a staff member—becomes justification for Dr. Hawthorne (Gibson Frazier) deciding to keep her a full week. Attempts to involve the cops—and, eventually, Sawyer’s widowed mother (Amy Irving)—prove fruitless. The only consolation comes from a fellow patient named Nate (Jay Pharoah), who’s being treated for opioid addiction.

The situation is made far worse, however, when David shows up at Highland Creek in the guise of George Shaw (Joshua Leonard), a mild-mannered orderly who’s a special favorite of hard-nosed Head Nurse Boles (Polly McKie). Or does he? Even Sawyer isn’t sure: her attempts to date, as we’ve seen, have ended in her going into hysterics, and she’s as likely to imagine Strine still stalking her as for Shaw actually to be him.

It wouldn’t be fair to reveal too many specifics about what follows, except to note that while “Unsane” resembles Hitchcock’s “Psycho” in having been made fast and on the cheap, it follows another of his films in revealing the truth quite early on. The problem is that Soderbergh’s picture is no “Vertigo,” and the result of letting the cat out of the bag halfway through isn’t a deepening of the mystery so much as a descent into the crudest devices of the thriller genre—not only chases down seemingly endless corridors and scenes of torture and captivity, but a series of climaxes piled atop one another that finally bring release and a grim twist at the close.

In a grimy, rather ugly way, “Unsane” is effective, but it’s also unpleasant and shrill. It lacks the cleverness of “Side Effects” and settles for coarse, obvious thriller clichés, with narrative twists that turn out to be remarkably unsurprising. It does offer up an ultimate institutional villain in Ashley Brighterhouse (Aimee Mullins), the facility administrator who’s more interested in protecting corporate profits than patient wellbeing, but even there it seems a cheap victory, given the cost in human terms.

Nevertheless it must be admitted that Foy gives Sawyer her all, registering the requisite span of emotions even if she can’t give much nuance to an underwritten character. Lawrence brings suitable creepiness to Shaw, keeping us guessing about him as long as the script allows, while Temple brings appropriate mania and Pharaoh an agreeable nice-guy quality to Sawyer’s very different fellow patients. None of the remaining actors, including Irving, fare especially well, but their opportunities are very limited.

So too are Soderbergh’s chances to shine. He might think that the camera possibilities of phones represent the future of moviemaking, but “Unsane” makes one long for the old techniques. When Hitchcock used television tactics in “Psycho,” the result was still visually striking, even beautiful. Those are words few are likely to think of when talking about the look of this movie.

Hitchcock, of course, was also working from a script that didn’t reveal the real nature of the Bates family relationship halfway in.