o direct one movie that is on everyone's lips in awards season is remarkable. To make two begins to look like sorcery. That is the position in which the 30-year-old Florida-born film-maker Lance Oppenheim now finds himself. Next month brings the release of You Can See Everything, the three-hour documentary which he co-directed with faux-naif deadpan prankster Nathan Fielder, in which they spend a month living with the disgraced health-tech mogul Elizabeth Holmes before she begins her 11-year prison sentence for fraud and conspiracy. The film, described by Oppenheim as "head-spinning" and so shrouded in secrecy that Variety magazine's list of Oscar predictions identifies one of its cast members only as "[Redacted]", is expected to become the first documentary nominated for best picture.

When I meet Oppenheim in a London hotel, it is to discuss his other hot ticket, Primetime, for which Robert Pattinson is the one attracting Oscar buzz. The Batman actor gives a high-wire performance as Chris Hansen, the sensationalist US television vigilante renowned for ambushing paedophiles on To Catch a Predator, which was a disreputable and highly addictive segment of the current affairs show Dateline NBC between 2004 and 2007. Hansen later parlayed the idea, and his crusading shtick, into a succession of spin-offs. Some, including Hansen Vs Predators, had the same sleazy catnip quality. Others, such as a sting to collar bicycle thieves, did not.

The format of To Catch a Predator is simple. A volunteer from the website Perverted-Justice enters an online chatroom pretending to be underage. Once a paedophile takes the bait, chats with the supposed teen and then pitches up at the agreed location (which is in fact a "sting house" rigged with cameras), he is met by an actor posing as the adolescent. Suddenly, Hansen slinks out of the shadows and calmly invites the offender to "have a seat," an offer which quickly became his catchphrase. He then reads aloud excerpts from the incriminating online chat as the guilty party squirms and panics. Reality television this may be, but it is also a theatrical performance with its own unvarying props from one sting to the next: cookies and pizza the pre-sex snacks, a table or kitchen island Hansen's equivalent of a CEO's desk or judge's bench.

"The show is so tonally strange," marvels Oppenheim. "It feels like an alien object beamed in from Mars. You're seeing this horrific situation where someone who's sick in the head has shown up to do a terrible thing. Then they're confronted by Chris Hansen, who has these catchphrases and one-liners. He's a crime-stopper but he's also there to make a TV show out of their miserable state. It oscillated between making me nauseated and making me laugh. The challenge for me was how to create something that's even stranger than stranger-than-fiction."

In person, you would never take this boyish chatterbox for a zeitgeist-surfing A24 auteur whose fanclub includes Ari Aster, Darren Aronofsky and the Safdie brothers. In fact, you might think twice before serving him alcohol, at least without ID. His mini pompadour gives him an Eraserhead Jr look; his black, round-framed glasses might have been felt-tipped on to his face by a classmate. A black-and-white striped shirt worn under his suit jacket lends him the appearance of a well-dressed humbug.

Though based in fact, Primetime is Oppenheim's first non-documentary feature. His haunting 2020 debut, Some Kind of Heaven, was set in a Florida retirement community where happiness becomes oppressive and tyrannical. Its 2024 follow-up, Spermworld, delved into the private lives of men who donate sperm, including one who has fathered more than a hundred children.

"I've always wanted my documentaries to feel like Hollywood dramas," the director explains. "With Primetime, I was curious about what it would be like to make an actual Hollywood drama with actors." The resulting character study is almost as kaleidoscopic and overripe as Ren Faire, Oppenheim's masterful 2024 HBO "docu-fantasia" featuring a mercurial, Viagra-popping elderly theme-park despot, his back-stabbing underlings and a giant talking lizard.

The film-maker's own introduction to Chris Hansen came as a child when he saw him spoofed on an episode of South Park, in which Cartman is strong-armed by the presenter into appearing on a TV special about Tourette syndrome; a group of paedophiles inadvertently come to his rescue by shooting themselves en masse. From there, Oppenheim became hooked on To Catch a Predator and its derivatives. A few years ago, his girlfriend (now wife) even bought him a personalised Cameo video message from Hansen. He scoots forward now to play it to me on his phone. In the video, the silver-haired paedophile-hunter cheekily invites Oppenheim to "have a seat … not because I suspect you of anything predator-like," before plugging his own upcoming shows.

It is this confusion between righteous avenger and meretricious huckster that makes Hansen such an irresistible subject. "I think he started off with noble intentions, but he turned serious reporting into entertainment and willingly transformed himself into a meme. He's on Cameo presenting what he does as a service you can pay for; then he puts his whole project into this moral register where he talks about good and evil. What happens to you psychologically when you believe you're doing something good for the world? Does that turn you into a superhero?" He grins: "And now we've got the guy who plays Batman as Chris Hansen."

It was Pattinson, already a diehard Hansen fan, who brought the project to Oppenheim intending only to produce rather than star in it. "Rob's quite possibly the actor of our time," the director says. "Every movie he's done this year has been a defining cultural moment." Primetime follows The Drama, his prickly black comedy with Zendaya, and The Odyssey; Dune: Part Three arrives in December. "As I've gotten to know him, I feel like he also stitched some very human and vulnerable parts of himself into Primetime. Rob became an overnight celebrity when he went to Comic-Con with Twilight in 2008. He was instantly a public figure with expectations about how he should behave. That's part of what Chris Hansen goes through in the movie."

The special alchemy of Primetime lies in the way it renders Hansen's story in the clammy style of To Catch a Predator so that we are simultaneously inside the show, with its churning moral tumult, and outside, looking on in appalled and impotent horror. "It is very much a biopic," agrees Oppenheim. "I wanted it to be experiential and phantasmagorical. I was wondering what would happen if you took Billy Wilder's Ace in the Hole, Oliver Stone's JFK and Brian De Palma's Body Double, then threw them in a blender with the real-life events of To Catch a Predator. Would it taste weird or delicious? Maybe you sprinkle a little Sexy Beast in there, too, and it's, like, 'Boom!'"

Boom, indeed. Hansen, who has griped bitterly about not being consulted or even informed about the film, has accused Primetime of "weaponised empathy", "[making] audiences feel sorry for the predators" and portraying him and his staff "as ratings-obsessed, maniacal people". On the other hand, he has insinuated himself enthusiastically into the Primetime experience, booking trailers for his own true-crime streaming platform, TruBlu, to run immediately before screenings of the movie in US cinemas.

Oppenheim is full of admiration. "The way he has created a media circus around his reaction to the film is on a par with what we've seen of him on television. He contains multitudes. He is a journalist but also an entertainer, a circus ringleader and maybe a compulsive performer." Are there parallels with the current US president? "Well, they were both on television around the same time and both on shows which were made or green-lit by Jeff Zucker, who plays himself in the film." He stops short, though, of calling them kindred spirits.

Perhaps Hansen's persona is too closely intertwined with the development of Oppenheim's own sensibility for him to make any such damning judgment. "I saw To Catch a Predator long before I saw Abbas Kiarostami's Close-Up or Orson Welles's F For Fake," he says, citing two films in which documentary and drama form an unstable concoction. "But I feel the show has a lot in common with them because it's such a reality bender. It has short adult actors pretending to be children in a house that looks like a set from Blue Velvet." He shakes his head as if experiencing afresh the insanity of To Catch a Predator. "I don't think I'd be making nonfiction films the way I do if I hadn't seen that show as a kid."

• Primetime is in UK cinemas from 30 October. You Can See Everything is in UK cinemas from 20 November