You can always count on Steven Soderbergh to do something unexpected and a little weird, and his new psychological thriller Unsane is no different. Shot on entirely on an iPhone, the mysterious movie is being billed as a horror film, starring The Crown breakout Claire Foy as a woman who believes she sees her stalker everywhere and inadvertently commits herself to a psych ward. Once she’s locked inside, she still sees her stalker around every corner and begins to wonder if her greatest fears are real or merely the product of delusions. The “is it real or am I crazy?” question is a rich cinematic tradition and the backbone of so much good psychological horror, so I’m excited to see what a filmmaker like Soderbergh can do with the concept — especially when he’s mixing it up even further by filming the whole damn thing on a smartphone. He’s not the first filmmaker to do it; Sean Baker’s Tangerine is staggering and Park Chan-wook did impressive work with the format on his fantasy short Night Fishing, but there’s something about the stark simplicity of it that seems perfectly tuned to Soderbergh’s style. It also works well with the psychological thriller vibe, giving the whole thing an intimate, unrefined feel. Watch the first Unsane clip below. The film also stars Joshua Leonard, Jay Pharoah, Juno Temple, Aimee Mullins, and Amy Irving and arrives in theaters on March 23rd.