Unsane

In between his big-budget blockbusters and prestige Oscar winners, Steven Soderbergh has always had a penchant for tinkering with side projects.

His latest tangential dalliance, the small-scale thriller Unsane, follows his recent commitment to no-frills filmmaking, which comes on the heels of a retirement threat a few years ago.

Soderbergh’s apparent disillusionment with mainstream filmmaking doesn’t mean his creative juices aren’t still flowing. His edgy new film was shot entirely on an iPhone — joining the immersive 2016 drama Tangerine in that distinction — providing a testament to technological advancements that even make something like this possible.

Yet despite a committed performance from Claire Foy (“The Crown”), the film turns into a mediocre saga about mental illness and female empowerment that lacks sufficient depth and context to resonate beyond a few surface thrills.

Foy plays Sawyer, a hot-tempered banker who has recently relocated across the country to escape some troubles from her past. She decides to visit a psychiatrist to sort out some feelings, then winds up involuntarily committed overnight to a behavioral health clinic.

She finds encouragement from a fellow patient (Jay Pharoah) who knows the ropes, and becomes aggravated by her unstable roommate (Juno Temple). Most of all, Sawyer is obsessed with a night nurse (Joshua Leonard) who reminds her of a shadowy figure she’d rather forget, which leads to a tormented downward spiral.

The iPhone visuals don’t feel like a gimmick, but rather give the material an appropriately gritty visual texture as the lines blur between fantasy and reality.

However, the screenwriting tandem of Jonathan Bernstein and James Greer (The Spy Next Door) starts with a One Flew Over the Cuckoo’s Nest vibe before offering a muddled exploration of knee-jerk psychology and a half-hearted indictment of greed and corruption within the health insurance industry.

The result is emotionally unsettling even as it gradually strains credibility and defies logic. Plus, there’s a bizarre cameo from a prior Soderbergh collaborator that comes out of nowhere.

Foy generates sympathy for Sawyer as she descends into madness. But while the final act is meant to keep moviegoers guessing about what’s real and what’s imagined, it doesn’t supply enough compelling twists or surprises to warrant such provocation.

Rated R, 97 minutes.