Quiet on set: Lights, iPhone . . . action!

FRESH from collecting the latest batch of awards for her brilliant performance as the Queen in the Netflix drama The Crown, Claire Foy gives a timely reminder of her impressive versatility in Steven Soderbergh’s intriguing low-budget thriller Unsane.

One of the reasons it’s intriguing is that it is shot entirely on an iPhone.

That could seem like pointless experimentation or even gimmicky affectation, but actually it makes sense, for reasons of visual as well as budgetary economy.

Foy is terrific as Sawyer Valentini, a spirited young American woman who finds herself ‘voluntarily’ committed to a psychiatric hospital. Sawyer has moved to Pennsylvania after abruptly leaving Boston to shake off a stalker (Joshua Leonard), but finds, in the hospital, that he might have been following her all along.

Cleverly, Soderbergh toys with our perceptions as well as Sawyer’s; she seems perfectly sane, but is the tormentor in her head?

A fine cast also features Juno Temple and Amy Irving, with a cameo for Matt Damon as a security adviser. The film, which contains certain distinct echoes of One Flew Over The Cuckoo’s Nest, ends up getting a bit overwrought, but it is nonetheless a fascinating addition to an already-eclectic list of directorial credits that includes Sex, Lies And Videotape, Erin Brockovich, Traffic, Behind The Candelabra and Ocean’s Eleven.

Most Soderbergh films are worth seeing — and this one is no exception.