Nathan Fielder is deadpan inside—or so he’d like us to believe. Fielder sets up The Rehearsal, his eccentric new HBO series, as an epic human experiment of which he is the nerdy master. Obsessively gathering data in flow charts, he goes to extreme lengths to prove that we could have total control over our lives, if only we could map out in advance all the possible permutations of a major life choice or event and then run the scenarios as a simulation.

“If you plan for every variable, a happy outcome doesn’t have to be left to chance,” Fielder intones earnestly, like a guy who’s overdosed on motivational guides. It’s a mode he perfected on Nathan for You, his cult Comedy Central series, in which he set himself up as a consultant proposing unorthodox and outrageous solutions for small businesses. But The Rehearsal takes the concept so far that it ventures into uncharted television territory. It’s impossible to know where fake ends and real begins.

The premise of the series is that Fielder helps strangers rehearse an impending major life event that is making them worry. His first volunteer is Kor, a 50 year old Brooklyn teacher who responded to a Craigslist ad asking, “Is there something you’re avoiding?” Kor feels guilty about having misled his trivia quiz team about his educational qualifications and needs help preparing to fess up to a particularly contentious team member. That sets in motion a crazy, ever-expanding process that includes constructing an exact replica of Kor’s apartment and the bar where he plays trivia, and hiring lookalike performers to act out the confession scene, playing through every conceivable action and reaction. Some of the funniest moments are the most unexpected—like the way Kor gets so absorbed in the fake trivia game Fielder has staged that he can’t concentrate on his emotional mission. Fielder ends up finding wacky ways to get around each new problem.

If The Rehearsal carried on in this problem-of-the-week fashion, it would’ve been cringe-inducingly funny. But instead, the show careens off the rails and into much murkier waters when Fielder recruits Angela, a single woman and devout Christian who is wondering what it would be like to raise a child. He creates an elaborate fantasy for her to “try out” parenting by dropping her in a house in Oregon with a “son,” played by a cast of child actors who will graduate up in age over the course of the rehearsal. In one of the creepiest visuals, someone climbs through the window of the baby’s room, takes the infant out of his crib and then replaces him with a slightly older baby.

I can’t fully describe what happens without squeezing some of the poetic madness out of The Rehearsal, but suffice it to say that the scale of the project spirals into a kind of Russian doll situation: worlds within worlds within worlds. Fielder becomes a dog chasing its own tail, spiraling through layer upon layer of meta like a man with existential OCD.

Every so often he takes us behind the scenes to glimpse the inner workings of the production: the constant contact with parents of the young actors, the legal paperwork, the flow charts anticipating potential developments, the search for actors. He even sets up an ersatz drama school in Los Angeles, The Fielder Method, to train performers for the intense level of realism The Rehearsal requires. When one of his students mentions the legendary acting teacher Stella Adler, Fielder plays dumb. “Stella Adler? What is her thing?”

The students’ prime assignment is to covertly stalk ordinary people and try to “be” them. But in order to refine his “method,” Fielder starts staging reenactments of his own classes. That way he can watch himself (or rather, someone impersonating him) and understand how the project feels from the actors’ point of view. Not only is he critical of himself (“He didn’t seem like he had ever taught an acting class before!”), but he starts to realize how puzzling his project must be: “Is this a show about an acting class?” he asks, in the guise of a student. “Am I supposed to be acting?” He also sees that handing out legal paperwork at the end of the first class might have felt intimidating to the broke actors, who felt compelled to sign without reading their contracts.

Although there are some uncomfortable laughs in the series, I wouldn’t classify it as a comedy so much as a genre-bending experience. I never quite knew what was real, how I was supposed to respond, or even what I felt. The show reminds me a little of an ethically dubious 2003 Bravo series called Joe Schmo, which put one sweet real guy named Matt in the center of a fake reality show, surrounding him with fellow “contestants.” They all turned out to be actors improvising around scenarios scripted by screenwriters—much like Fielder’s gang.