When you hear about a movie called “Personal Shopper” starring Kristen Stewart of “Twilight” fame as a lonely gal who buys shoes and dresses for a world-famous celebrity, you might well think I’m talking about a light romantic comedy — the kind of vehicle a Sandra Bullock or a Katherine Heigl might once have driven.

Not. Even. Close.

Kristen Stewart’s performance in this film is in a universe beyond the bite-the-lip, minimalist-schlock work she delivered in the “Twilight” movies, and this film masterfully delves into a number of genres, none of them light romantic comedy.

It’s a brilliant character study, a devilishly confounding murder mystery, a legitimately haunting psychological thriller, a hell of a ghost story — and one of the most memorable viewing experiences I’ve had in the last few years.

I rarely tell you a movie is unlike anything I’ve seen before because that’s almost always hyperbole, but trust me, writer-director Olivier Assayas’ “Personal Shopper” is unique and memorable, and really, really weird, in a great way.

Stewart plays Maureen, who favors straight-leg jeans and high-top gym shoes and the kind of hairstyle favored by rebellious teenage boys of a bygone generation. Maureen is sullen and somewhat closed-off, and she speaks in an unnervingly direct tone, whether she’s engaged in everyday conversation, Skyping with her faraway boyfriend — or trying to establish contact with her dead twin brother, Lewis.

You see, Lewis was a medium, and Maureen was a medium, and they were extremely close, even for twins. They shared the same heart condition, which took Lewis while he was still in his 20s, and they had a pact: Whoever died first would try to make contact with the other one, to prove there’s some kind of afterlife.

In a dark, creaky, rambling house where Lewis once lived, Maureen wanders about in the shadows, trying to establish contact with Lewis. I’m not saying if it ever transpires. Let’s just say that what eventually DOES happen will quite likely make you jump in your seat.

Maureen has a day job as a personal assistant/shopper for Kyra (Nora von Waldstatten), an internationally famous and self-absorbed diva who is almost never around, even when she IS around. (She barely acknowledges Maureen when Maureen enters a room, other than to say she wants to keep expensive items that were loaned out, and can Maureen make that happen?)

As Maureen zips around Paris and makes day trips to London in search of $2,500 belts and even more expensive handbags and dresses for her client, she begins to receive text messages from a mysterious stranger who may or may not be of this world. The text exchanges are funny and creepy and sexy and strange and filled with tension — and the manner in which they’re filmed proves one CAN turn text messaging sequences into exciting cinema. It’s compelling stuff.

Maureen has an almost fetishistic desire to try on Kyra’s things (an explicit no-no), and she confesses that need to the mystery texter, and then acts on her fantasy in a beautiful and erotic scene that’s infinitely sexier than anything we’ve seen in either of those dopey “50 Shades” movies.

Meanwhile, somebody or something from the spirit world is getting increasingly aggressive with Maureen. Her matter-of-fact manner when dealing with the afterlife gives way to sheer terror, to the point where this previously ice-cold cool cat is now curled up in the fetal position, hoping for it all to STOP.

If you stopped paying attention to Kristen Stewart’s career arc after the “Twilight” films, you’ve missed a number of wonderful performances in a diverse and very fine array of films, from “On the Road” to “Clouds of Sils Maria” (her first partnering with director Assayas) to “American Ultra” to Woody Allen’s “Café Society.”

Stewart rises to the next level with her startlingly excellent work in “Personal Shopper.” She is in command of her character, sometimes almost casually so, keeping us focused on every little bit of physical business, every interesting choice of line readings, every moment of vulnerability that begins to bleed through the self-protective exterior. Stewart was the first American actress to win the Cesar (essentially the French Oscar) for her work here, and she deserves an Oscar nomination as well.

Some of the mysteries presented here are answered in the most direct manner. Others … not so much. At times we wonder if Maureen is imagining some of the things happening to her. Other times, we question the motivations of seemingly sympathetic characters in her life.

And then there’s the matter of Lewis, who is dead but is one of the most perplexing and fascinating pieces of the psychological puzzle. To the very end of “Personal Shopper” and well into the discussions you’ll want to have with others who have seen it, there’s much room for interpretation.

I can’t explain everything I saw in this film, but I was entertained and enthralled by every second of it.

★★★★

IFC Films presents a film written and directed by Olivier Assayas. Rated R (for some language, sexuality, nudity and a bloody violent image). Running time: 105 minutes. Opens Friday at local theaters.