Juliette Binoche knows how to blur the lines of fact and fiction—indeed, she’s made a career of it. In films ranging from Michael Haneke’s Code Unknown to Abbas Kiarostami’s Certified Copy to Olivier Assayas’s Clouds of Sils Maria, the Oscar winner has spent decades confronting changing realities before the camera, with art and performance bleeding into her characters’ everyday lives. She’s particularly dynamic in such roles—slippery and hard to pin down as the ground shifts beneath her, but always emotionally present and intuitive. “It’s a theme that, as human beings, we have to deal with,” Binoche says now. “Acting is all about putting everything on the table. I don’t know anything—and I want to explore what I don’t know.”

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There’s an ingenious layer to her casting, then, in The Staircase, HBO Max’s dramatization of the death of Kathleen Peterson (Toni Collette) at the bottom of her home’s staircase and the ensuing murder trial of her widower, Michael Peterson (Colin Firth). (Michael was found guilty by a jury, but was later released from prison after being granted a new trial and submitting an Alford plea.) Along with the fallout experienced by the Peterson family, The Staircase explores the making of the French docuseries about Michael in the aftermath of Kathleen’s death, a meta element that aids in the series’ broader focus on how complex crime stories are packaged and consumed when the truth of what happened is so elusive.

Binoche portrays the documentary’s editor, Sophie Brunet, who’s depicted as falling in love with Michael over the course of filmmaking. The actor signed on having little idea of what was coming in the show, beyond broad strokes of the character’s arc. (Sophie does not appear much in the first three episodes; in fact, critics were asked not to spoil the identity of Binoche’s character in pre-air reviews.) And it’s her first-ever series role, aside from playing herself in a Call My Agent! episode. Binoche had avoided TV for the entirety of her nearly 40-year screen career because it felt totally separate from film, until recently; she was thus surprised when Staircase creator Antonio Campos asked her to come aboard. Yet Binoche, who has asserted herself as one her generation’s most versatile and skilled actors since winning the Oscar for 1996’s The English Patient, isn’t one to turn down a new challenge. “I wanted to go into the adventure, because you want to try new things as an actor,” Binoche tells me. “I didn’t read all of the episodes because they were not written yet. So I decided to jump into it not knowing what was going to happen. I was going into the unknown world.”

A highly regarded editor in French cinema, Brunet spoke with Campos for background on her 13-year relationship with Michael (they’ve since broken up), but did not want to be a character in his show. Still, she reluctantly agreed to talk with Binoche upon learning the actor would be playing a version of her. The two women lived a mere 10-minute walk away from each other, it turned out, and first met in Brunet’s garden. They talked for hours. Binoche found Brunet straightforward, candid, and free-spirited; Brunet sensed a blossoming new friendship.

Closer to filming, Binoche decided to take this budding relationship to the next level—both for the work and maybe the company. Binoche had just conducted a video interview with Michel Ocelot, the French animator, for a film festival, and asked Brunet to edit it. “We worked together for a big, long week,” Binoche says. They cut the piece together, and Binoche watched how her subject really worked. They chatted a lot too—about Michael, about the process of editing, about the show Binoche was about to make.

They got close—which, Binoche would come to learn, made the process of actually playing Brunet more complicated than the actor bargained for.

Sophie develops into a pivotal role in The Staircase, representing the doc filmmakers’ perspective as she balances her professional obligations with her romantic relationship. In other words, Binoche drives the most controversial element of the sprawling series. The Staircase docuseries’ director, Jean-Xavier de Lestrade, who’s credited on the HBO Max series as a co-executive producer and shared footage with the creative team, told Vanity Fair last month that he felt “betrayed” by Campos and co-showrunner Maggie Cohn’s version of events. He called the depiction of Sophie’s feelings for Michael informing the way she edits him an attack on his and Brunet’s “credibility.” Brunet also told Vanity Fair that the show does not hew to the reality of her conduct regarding Michael.

Before production, Binoche watched the docuseries over and over; as with anyone who’s seen it, the more she saw, the less sure she was of anything. She at least had a firm grasp on Brunet and her story. Arriving in Atlanta to film in spring 2021, though, Binoche gleaned that the show’s interests rested less in straightforward facts than competing truths, a hallmark of the Peterson case—and of Binoche’s art house career.

The power of narrative—of fiction—fuels The Staircase’s thorough deconstruction of true-crime hysteria. Binoche was tasked, then, with portraying someone whom she’d come to know and admire—only to then act out scenes she knew did not correspond with reality. “The big question is, when you do a fiction out of a reality, what are your rights?” Binoche says. “You can do an adaptation of a novel to a film, but it’s quite different when it has to do with a person’s life. And I felt like an advocate for Sophie.”

Becoming friends with Brunet—whose last name is not used in the series—meant Binoche knew what to stand up for. She highlights to me Sophie’s “perfect deontologic mind and heart,” her commitment to separating her work from her personal life—which the show depicts as not quite being the case. The back-and-forth with Campos and Cohn was “not easy,” in turn, even as Binoche found the showrunners receptive to her concerns. She felt conflicted: as devoted to the series’ artistic license as she was to Brunet’s own truth. “Sometimes I would say to Antonio, ‘This is not the way it happened!’ And he would say, ‘Yes, but it’s not about that.’” Binoche spoke with Brunet over the course of filming, relaying that certain scenes weren’t lining up with real life: “I was saying to Sophie, ‘I’m trying the best I can, but it’s going to be different than your life.’”

While emphasizing “the freedom that showrunners need,” Binoche expresses empathy for those involved who’ve come out against The Staircase. (Michael Peterson himself, his lawyer David Rudolf, and various Peterson children have also strongly criticized the show.) “I totally understand the pain of being in a fiction that is talking about your life, and yet it’s not your life,” Binoche says. “I understand the pain of Michael Peterson’s children, who have to deal with a situation that has been fictionalized.” In regard to making art like The Staircase, though, she later adds: “It’s all about transforming your perceptions of things. If you try to block the mind to make everything so perfect or rational, then you’re not alive anymore.”

And Binoche is nothing if not alive in The Staircase. In the character of Sophie, between her own research and Campos and Cohn’s nuanced depiction, the actor viscerally performs a building sense of internal agony. Sophie becomes more invested in Michael’s freedom as the show goes on. They write each other letters while he’s in prison; she all but moves to his hometown of Durham, North Carolina, putting her Paris life in limbo. She chases alternate theories for Kathleen’s death, and later pushes him to take the Alford plea and leave the possibility of further imprisonment behind. (Binoche echoes Brunet’s claim that she didn’t actually ask Michael to accept the plea: “It’s not her spirit.”)

Intriguingly, Sophie drives the infamous “owl theory” within the HBO drama by learning and debating its merits. By the end of the hour, she’s fully convinced it explains Kathleen’s bloody demise. (Binoche says this reflects Brunet’s true feelings about the theory being credible.) But the episode hinges on a major departure from the record by having Sophie ask Kathleen’s daughter Caitlin (Olivia DeJonge) to exhume her mother’s body for further examination. Brunet did not—and would not ever—do this, Binoche insists. (In the show, Caitlin angrily declines.)

“I said to Antonio, ‘As a mother, you would never do that. You never ask a daughter for permission to exhume her mother’s body.’ But in the course of a TV series, you’ve got to put one episode to the next one and the next one, so people are interested,” Binoche says. “I actually asked them to rewrite the scene.” They worked on it some, but with the same final result—Sophie making the request of Caitlin—Binoche still struggled with how to play it. She leaned toward realizing the moment as a kind of breakdown for Sophie—a last resort. In Binoche’s teary eyes, you see how hard it is for Sophie to ask Caitlin, that she knows it’s wrong; in her bluntness, you also see that she feels out of options. This is the only way.

Such contradictions speak to the power of Binoche’s performance here and throughout The Staircase: She’s an open wound, determined and at times desperate; Sophie gets more and more lost in the maze of a case that’s confounded the world for two decades, to heartbreaking ends. Binoche lets it all out, episode after episode. “I thought that what Sophie gave into Michael’s life was her heart—she did everything she could,” Binoche says. “She really gave herself, and I felt like, emotionally, I needed to give Sophie what she gave.”

Binoche has now filmed her second TV series in a row, as the lead role of Coco Chanel on Apple TV+’s forthcoming The New Look. She’s sworn to secrecy here, but calls the work intense and exhausting. Once more, she sifted through dozens of perspectives on her subject’s actual biography and who she really was, in an effort to settle on an honest and realistic portrait. “With Sophie, it was easier because it was horizontal—I just do 10 minutes of walking and I’m at her place,” she says with a laugh. “But with Coco, it’s vertical. I’ve got to try to catch up with her, because she’s not here to say what she feels and what was a reality.”

“She was always hiding the truth of her life,” the actor adds. Surely, though, we can trust Binoche to find it.