The title of Her, Spike Jonze’s excellent but deceptively dark new film, is less anodyne than it first appears: the antecedent of that pronoun is properly not a her but an it. “Her” is Samantha, or rather “Samantha”—a computer/smartphone operating system, voiced by Scarlett Johansson in her signature New York contralto, developed some time in the near future and purchased by Theodore (a finely withdrawn Joaquin Phoenix), who soon falls in love with her. Deviously elliptical, Her is easily the best of Jonze’s four feature films, which until now have felt like overextended versions of his superior music videos—achievements such as the Beastie Boys’ “Sabotage” or Notorious B.I.G.’s posthumous “Sky’s the Limit,” whose invention was thrilling at four minutes but insufficient for two hours. It looks gorgeous, too, saturated with glittering shots of a futuristic Los Angeles are infused with the same melancholy beauty that Jonze’s ex-wife Sofia Coppola brought to the Tokyo of Lost in Translation. Yet Jonze’s generous portrayal of the emotional power of new technologies obscures a much creepier core. The whole film is a horror story dissembling as a romance: even more than Gravity, more than Texas Chainsaw 3D, Her is the scariest movie of 2013.

In Jonze’s near future, computers, smartphones, and other devices are voice-activated, and users wear a small headset in one of their ears as they mumble their way through the streets. At first Theodore’s devices run on an operating system that requires him to speak simple commands such as “Read email” or “Delete,” but soon he upgrades to a new, artificially intelligent operating system, called OS1 and produced by a company called Element Software. The selling point for OS1 is its ability to learn and mature through experience, growing smarter and more sophisticated with use. “It’s not just an OS. It’s a consciousness”—so goes the tagline for OS1, and note the pronoun choice.

Yet the phrase “Element Software” is never used again in Her, and for the remainder of the film commercial, legal, and political questions are totally, intentionally pushed to the side. We never see Theodore buy the software. We never see him accept an end-user license agreement, one of those near-infinite contracts none of us ever read. Instead Jonze skips directly to Theodore booting up the new OS, which, in Johansson’s voice, identifies herself (I feel manipulated using that word, but itself seems impossible) as Samantha. She reads his emails, edits his work, reminds him that he has an appointment in five minutes, but soon the relationship deepens: when Theodore goes on a date with a woman—an actual woman, not an OS with a woman’s voice—he’d clearly rather be with his gadget. The first time they have sex the orchestral score swells and the screen fades to black, sparing us the actuality of the sexual encounter: “I feel you inside me,” Samantha moans, but of course what’s really taking place is an act of masturbation.

Samantha, by this point, is speaking to Theodore in the language of feelings and desires—what she “wants” from him, how she “needs” him. And you could have lots of philosophical fun debating whether an artificial intelligence can have emotions or merely exhibits behaviors that look like emotions. (As Jonze cunningly appreciates, the computer gets the benefit of the doubt when it has the voice of Scarlett Johansson). You can ask, too, about the value of Theodore’s love for Samantha—which Jonze depicts not only as legitimate but as morally improving. Yet what makes Her so powerful and so scary is that these admittedly important questions obscure, by design, the deeper and darker issues of economics, law, and citizenship that such software raises.

That sex scene, for example: while we wonder about the mechanics of their intimacy or the implications of love for a machine, somewhere out of frame Element Software is presumably logging every second of the encounter, just as it has surely mined the emails Samantha has read or the images she has analyzed. As Theodore begins to use the OS nonstop, even sleeping with it—less creepy when that it feels like a her—not just his data but his entire life become a form of economic production for an unseen company. Not unlike the now-public corporations known as Facebook and Twitter, Element Software derives the totality of the revenue from Samantha’s content, while the seduced Theodore offers his most private self to Silicon Valley, gratis, just to hear her (its) voice.