The comedian Nathan Fielder loves to sit just a hair too close to people. Often, these are people he barely knows. In an episode of “The Rehearsal,” his mind-bending, genre-defying HBO show, in which he helps participants prepare themselves for meaningful life events before they take place, we see Fielder recline in his stocking feet on the twin bed of a young pilot he’s just met, his legs tucked girlishly, as the other man perches uncertainly beside him. In the finale of “Nathan for You,” the Comedy Central show in which he offers ludicrous advice to failing small businesses, he shares a small hotel room with an elderly near-stranger whom he’s helping search for a long-lost love. (“This is kind of a fun trip, huh? Just the boys?” Fielder goads the expressionless senior.) Later in the episode, when Fielder brings an escort back to the room, he scoots near her on one of the beds, making unbroken and unnerving eye contact all the while.

There’s something inherently comical about this insistent, creepy overfamiliarity. (It’s not surprising that a screenshot of the bed scene from “The Rehearsal” has become a popular meme.) Fielder’s willful disregard of conventional social norms—his comfort with an atmosphere of discomfort, to the extent that he is able to carry on as if nothing is amiss—elicits laughs in the same way as the punch line of an old joke that I recently heard: a urologist tells his patient he must stop masturbating. “Why?” the patient asks. “Because I’m talking to you!” the doctor responds. (Fielder, of course, is the patient.) But there’s also something puzzling, and unsettling, about the forced intimacy that Fielder likes to enact: it creates a tension that fuels his comedy but that lingers long beyond the laugh. What game is he playing, we wonder, and to what ends?

In his odd, gripping, and entirely original new documentary, “You Can See Everything,” which he co-directed with the filmmaker Lance Oppenheim, Fielder’s penchant for invading his interlocutors’ personal space is more pronounced than ever before, and, at nearly three hours long, the film gives us ample time to try and figure out his motives, as well as those of his subjects. Unlike his past work, however, “You Can See Everything” isn’t very funny at all. Instead, it’s a haunting exploration of the limits of other people’s knowability. How close can we really get to those around us? Where do we begin and where do they end? Are each of us, ultimately, all alone in the world, mere islands unto ourselves?

The documentary starts in medias res, with a man’s face in tight closeup as he speaks on the phone. This is Billy Evans, a Silicon Valley entrepreneur and the life partner of Elizabeth Holmes, the disgraced founder and onetime C.E.O. of the health-care startup Theranos, who, in 2022, was convicted of four counts of fraud. (Holmes deceived investors by making false claims about the capabilities of Theranos’s proprietary blood-testing device, which, she said, could detect a whole slew of ailments with just a pinprick’s worth of blood.) It’s now April, 2023, just more than a month before Holmes is set to begin serving her eleven-year federal prison term, and Evans, as he tells whomever is on the other end of the phone line, thinks that people need to understand who Holmes really is. If they did, they certainly would see that she is “so true and so good,” as he murmurs to her, a bit later. To that end, the couple have invited Fielder, Oppenheim, and a film crew into their Del Mar, California, beachfront rental, to document their lives with “radical transparency” and “as much access as possible.”

The film finds its subjects at a very fraught moment. Holmes, who is still nursing the younger of the couple’s two small children, is filing challenges to her conviction and taking calls about what to expect in prison. Evans, meanwhile, is focussed on getting “the band back together” to continue developing, with Holmes’s help, a new device providing low-cost blood-testing, which he refers to as “Theranos 2.0”—a startling example of Silicon Valley hubris, considering how well 1.0 turned out. For the couple, however, this makes sense—Holmes, they both insist, is completely innocent. (The implication is that her former partner in both love and business, the much older Ramesh [Sunny] Balwani, Theranos’s C.O.O., who was convicted of twelve counts of fraud, is the one responsible for the company’s wrongdoing.)

“The world believes a reality about me that isn’t true,” Holmes tells Fielder. He isn’t convinced by her protestations (“there is a lot of evidence that points to the fact that you defrauded investors and also deceived, you know, regulators and the public and patients,” he says), and he skulks around darkly, his surveilling presence casting a pall on the Holmes-Evans ménage. In scene after scene, Fielder, who fully moves into the house, grills the pair, together or separately—in their kitchen nook, in their marital bed, on their living-room couch—often at such proximity that they can surely feel his warm breath on their cheeks. A bit of this is still comical, and it certainly serves as a self-conscious callback to Fielder’s popular reputation as a possibly sinister weirdo. Running roughshod over domestic conventions, he sometimes seems like the couple’s overgrown son, recalcitrant and lacking in boundaries. (I laughed when, a few hours before Holmes is scheduled to surrender to the authorities, the comedian finally offers to give the couple some space so that they can “have sex,” and proceeds to go sit in his car with the music blasting—a move that reminded me of his “Nathan for You” scheme to create a “sex box,” in which parents can have intercourse while on vacation with their children.)

Mostly, though, we’re dealing with dead-serious business here. This is certainly the first time that a Nathan Fielder project has reminded me of a Bergman film, and that might be at least partly because of Oppenheim’s involvement. In his previous documentaries, such as “Some Kind of Heaven” and “Spermworld,” and in his recent narrative feature “Primetime,” Oppenheim is a stylish visual thinker and a master of vistas; in “You Can See Everything,” he turns largely to the vista of the human face. With the help of David Bolen’s eerily beautiful cinematography, Oppenheim, like Fielder himself, aims to get as close as possible, homing in, “Persona”-style, on the protagonists’ features, expressions, and gestures as a kind of window into their souls.

Holmes’s soul, however, remains a cipher. Who is this woman, with her wide, unblinking, cornflower-blue eyes, with her frequent tears and earnest proclamations, who keeps insisting on her utter sincerity—going so far as to say that she can’t remember telling a single lie? “She’s really weird. She’s just not normal,” Evans tells Fielder, while attesting to Holmes’s honesty, but the idea of full transparency—the notion that one can and will see everything about another person if there is willingness on both sides to do so—is both troubled and troubling in the film. The more access Holmes allows, the less Fielder is, seemingly, able to know her.

One pathway to enter another person’s consciousness is through the figure of the double—or Fielder, at least, seems to think so, when he tries to understand Holmes via the lens of his own subjectivity. “I’m a bad communicator,” he tells her at one point. “I don’t know a lot of words. Is that what you’re like?” (He also echoes a common reaction to his own tactics in the course of his career, when he wonders whether Holmes is “fully sincere” or “the most manipulative person who ever lived.”) Later in the film—and be warned of some spoilers from here on out!—he attempts to understand his subject by engaging with another double of hers, the actress Amanda Seyfried, who portrayed Holmes in the 2022 Hulu series “The Dropout.” It also becomes clear that Holmes and Evans see themselves as doubles of each other, claiming that the connection between them is practically telepathic.

Is this type of thinking delusional? Does it, at the very least, involve some mangling of an individual’s dearest, most private core? “You’re a very talented actress, very good performer, but, you know, you’re not her,” Fielder tells Seyfried, a rare admission by the comedian that his method has limits: a double, however convincing, may obscure its subject just as much as it reveals her. He recounts a conversation he had with Holmes, in which he compared his uncertain feeling while talking to her—was she telling him the truth or fooling him?—to a magic trick that he once saw David Blaine perform. Blaine appeared to be driving an ice pick through his hand, which viewers assumed relied on smoke and mirrors. In fact, Fielder says, Blaine was literally stabbing his hand, puncturing his own flesh to create the illusion of an illusion.

Watching this scene, I thought of Theranos’s promise to provide people with crucial medical knowledge through a tiny blood sample. This promise, as we now know, was fraudulent. No puzzles were solved; blood, it turned out, would not tell, and the mysteries of the self remained locked within it. Fielder, too, resists being known: after spending weeks trying to get into his subjects’ heads, he dismisses the possibility that they’d be able to get into his. “I know what you’re feeling,” Evans tells him, at one point in the film. Fielder’s response is immediate, and notably heated: “No, you don’t.” ♦