In Personal Shopper, Kristen Stewart plays her most confounding character to date: a grieving psychic moonlighting as a high-fashion buyer.

Oh, and did we mention she also might be texting her dead brother?

“To play that was interesting, because I had no way in preparing for it. It was just being willing to be the most lonely and isolated you could ever possibly imagine,” says Stewart, 26, who continues her recent streak of offbeat fare in the supernatural thriller (in theaters Friday in New York and Los Angeles; expands through April, adding Boston, Chicago, Washington, San Francisco, Seattle and other cities on March 17).

Fortunately, she had a cheerleader in French director Olivier Assayas, who wrote the character of Maureen with the Twilight star in mind after working with her on 2014’s Clouds of Sils Maria (for which she won a César Award, the Oscars’ French equivalent).

Reteaming with Stewart, “I was excited about the idea of trying with her something that is multi-layered, because she is an actress of great depth and subtlety,” Assayas says. “I thought she could express things way beyond what we did together on Clouds of Sils Maria.”

When Maureen isn’t delivering couture clothing to a supercilious celebrity model (Nora van Waldstätten), she spends her days trying to make spiritual contact with her twin, Louis, who died of a congenital heart defect. Events take an eerie turn when she starts getting text messages from an unknown sender, whose acute knowledge of Maureen’s life and whereabouts lead her to believe it’s Louis’ ghost.

Texting for long, mostly silent scenes, “my fear was that it’d be boring and unengaging,” Stewart says. As a result of Maureen’s overwhelming grief, “it’s hard to track who she thought she was dealing with at any given moment, whether she was battling herself or the memory of her brother or this anonymous presence that’s a threat. … It’s like, ‘Is she just making it up? Is she talking to herself?’ If you go through this insane loss and trauma, it’s a catalyst for stuff that you never really had before.”

Shopper’s release caps off a momentous last year for the in-demand actress, who recently worked with Woody Allen (Café Society) and Ang Lee (Billy Lynn’s Long Halftime Walk). In January, she premiered her directorial debut — a short film entitled Come Swim — at Sundance Film Festival, and hosted Saturday Night Live for the first time last month.

“This year has felt so good,” Stewart says. “I had been avoiding the idea of doing SNL for years because it felt so intimidating and I didn’t think it was necessarily in my realm. But I couldn’t avoid it anymore because I couldn’t think of a good reason not to, other than just being a wuss.”

The unassuming star delivered one of the most memorable monologues of the season, even if her jabs at President Trump were overshadowed when she dropped the F-bomb.

“It was funny, because I got through every single dress rehearsal without (swearing),” Stewart remembers. “Before we actually went live, every single person was like, ‘You’re going to do great, it’ll be over in an hour, and please, please, please don’t say (the F-word).’ I was like, ‘I won’t, trust me, there’s no way.’

“And, of course, (I did) in the first five minutes.”