At this point, people who follow cinema know to manage their expectations when anyone prominent claims they’re leaving the film industry. Steven Soderbergh said he was retiring from filmmaking back in 2013, but he returned to the big screen for 2017’s heist film Logan Lucky. He’s also stayed active in television with The Knick and Mosaic, and now he’s back with the horror movie Unsane. It seems like all he needs to be drawn out of retirement is some new piece of technology or filmmaking idea he wants to explore. With Unsane, that technology is… the iPhone.

In Unsane, a protagonist played by Claire Foy (The Crown, Wolf Hall) is dealing with a digital stalker who won’t leave her alone. Her attempts to get law enforcement involved somehow leads to her being confined in an institution, in the tried-and-true “Who’s really insane here?” plot. The same plot that gave the world terrific films like 1965’s Bunny Lake Is Missing and Alfred Hitchcock’s The Lady Vanishes, and less terrific films like Flightplan and A Cure for Wellness. There’s a little current social resonance in Unsane’s premise, where a woman says a man is abusing her, but she’s written off as delusional. Everyone who’s felt the backlash from the #MeToo movement and the post-Harvey Weinstein sexual abuse stories can probably relate to a harrowing tale of being gaslighted and told “He’s not doing anything untoward here, you’re just being hysterical.”

But the more resonant, up-to-the-moment fact here is that Soderbergh shot this film entirely on iPhones, which he’s hailed in interviews as the future of filmmaking. “Anybody going to see this movie who has no idea of the backstory to the production will have no idea this was shot on the phone,” he said in an appearance at the 2018 Sundance film festival. “That’s not part of the conceit.”

Judging from this initial trailer, Unsane looks fairly grainy and grubby, which appears to be part of the aesthetic point. Foy’s character is clearly caught in a dark and unpleasant place, which may be reflective of her state of mind, or of the lax standards of a mental health ward that takes its direction from crazed stalkers. But Soderbergh is proud both of the film’s visual quality and the ease with which he made it. “I look at this as potentially one of the most liberating experiences that I’ve ever had as a filmmaker,” he said at that Sundance session. “The gets that I felt moment to moment were so significant that this is, to me, a new chapter.”

Unsane will arrive in theaters on March 23rd, 2018.