Back in June, Errol Morris told me that, formally speaking, little had changed in the true-crime genre since he launched it to prominence with 1988’s The Thin Blue Line—and that with his upcoming return to such terrain, “I like to think that I’m trying to break new ground here. We shall see!”

As it turns out, he’s more than fulfilled his ambition.

Absurdly denied a shot at documentary Oscar glory because of its exceptional nature, Wormwood is a hybrid of the most thrilling sort, a work that melds nonfictional and fictional elements into a uniquely evocative experience. As such, it’s fitting it arrives this Friday (Dec. 15) in two nearly identical versions: as a 241-minute theatrical movie, replete with an intermission, and as a six-part Netflix-exclusive miniseries.

Constantly straddling the line between different modes, the film employs a stellar cast (led by Peter Sarsgaard, Molly Parker, Tim Blake Nelson and Bob Balaban) for unnerving dramatized sequences that are interspersed amidst Morris’ documentary segments. Like the image-based projects of its primary interviewee, it’s a psychologically penetrating collage, using juxtapositions of various materials to convey both external and internal truths. Oh yes, and it’s also a fascinating murder-mystery, one involving heinous crimes, covert coverups, and fanatical quests, all of it imbued with the oh-so-bitter biblical import implied by its title.

It is, in short, a pioneering masterpiece.

Morris’ subject is the death of Frank Olson (played, in reenactments, by a fantastically frazzled Sarsgaard), a government biochemist who, on Nov. 18, 1953, took a plunge out the window of his 13th-floor room in New York City’s Hotel Statler. It was ruled a suicide, and for the next two decades that’s what his wife Alice, son Eric, and two other children believed. That all changed in 1975, however, with the release of the Rockefeller Commission Report, which revealed that the CIA had in fact dosed Frank with LSD—without his knowledge or consent—as part of a misbegotten MKUltra mind-control program aimed at deducing whether agents could be pharmaceutically coerced into divulging state secrets. A national scandal ensued, resulting in an Oval Office apology from President Ford to Eric and his clan, which was accompanied by a $750,000 settlement.

Frank’s final days were spent at a hush-hush retreat at a cabin at Maryland’s Deep Creek Lake (where the acid was dropped), followed by a longer stretch in Manhattan under the watch of colleagues, who claimed they were concerned about Frank’s state of mind. Those incidents are detailed with stylish foreboding by Morris, whose main guide through this tangled tale is Eric Olson, interviewed in a number of Spartan, wood-paneled interior spaces. As Eric lays out, his father Frank had grave suspicions about the U.S’s use of biochemical weapons in Korea—and considerable guilt over his part in that war effort. And, at least in 1975, it appeared to Eric that it was those misgivings that had led the government to get Frank high in order to deduce whether, under narco-duress, he’d develop loose lips—a scheme that wound up having terrible unintended consequences for all involved.

Except that, as Eric came to learn, Frank’s accidental death may not have been so accidental after all. Wormwood is thus, on the one hand, a reportorial investigation into what actually happened inside the Hotel Statler’s Room 1018A on that fateful 1953 night—a mission facilitated by commentary from Olson’s lawyers and friends, as well as journalist Seymour Hersh, who first tackled the story back in the mid-1970s.

Morris’ latest is a veritable avalanche of facts, figures, and conflicting accounts, as well as a dive into ever-deeper clandestine realms, where sinister agents manipulate comrades and outsiders alike through canny misdirections. By the time Morris’ opus arrives at its post-1975 passages, it’s already unearthed a collection of seedy deceptions—and then, in 1994, Eric begins literally digging, exhuming his father’s body to determine whether Frank was the victim of foul play.

On a purely narrative level, Wormwood is consistently gripping and eye-opening, but what truly elevates it to the realm of greatness is Morris’ boundary-pushing storytelling approach. The director’s dramatic reenactments are crafted with canted angles, constricting framing, Zack Snyder-esque slow-motion, and film-noir shadows, which (together with a score of strings, piano, and apocalyptic braying tones) lend the proceedings a dreamy malevolence. Moreover, these staged sequences are all set in 1953, the better to create a heightened contrast between Frank’s speculative past (and Eric’s memories of it) and Eric’s more literally verifiable later activities, which Morris relates through nonfiction means. The result is a dynamic interplay between the real and unreal, the known and the unknown—one augmented by excellent performances that eerily channel the actions (and emotions) described by Morris’ incisive speakers.

Wormwood’s aesthetic daring, however, goes many steps further. There are split-screens that fracture the frame, presenting dramatic and verité moments side-by-side, as well as interviews (shot without the use of Morris’ favored Interrotron device; the director is often seen on-camera) from a variety of prismatic angles. There are numerous montages assembled from newspaper headlines, newsreel footage, and home movies, full of overlapping and intertwined imagery. And there are also frequent cutaways to expressionistic shots of clocks, squiggling microbes under a microscope, faded photos, and gas-masked technicians carrying out their biochemical duty—not to mention recurring clips from Martin Luther, Out of the Past, The Manchurian Candidate, and Laurence Olivier’s Hamlet, whose protagonist (spurred to vengeance by his murdered father’s ghost) serves as an apt fictional echo of Eric himself.

Through this unconventional patchwork excavation-cum-inquiry, Morris not only recounts events but also imparts a complex impression of twisted individual, institutional, and national psyches. His film is at once an exposé of governmental treachery—and the lengths to which authority figures will go to shield the public from their malfeasance—and of Eric’s self-negation-through-obsession, as his attempts to uncover his father’s fate eventually consume his life, and identity. It’s a portrait of the untrustworthiness of the powers-that-be, the unreliability of memory, and the price of pursing a single goal at the expense of all others, refracted through a hypnotic, hallucinatory mélange of sights and sounds that Morris has constructed with a deftness that’s awe-inspiring.

And then, having plumbed the subconscious of Eric, his distraught father, and the men—and establishment—that sought to silence him, the film ultimately becomes something even grander, and more haunting: a lament for the fact that, while truth does exist, that doesn’t mean it can be attained, at least in any meaningful public sense. “It’s wonderful to not have an ending,” opines Hersh in the late going, and the awful reality of that statement casts a terrible pall over Wormwood.

Redefining what a documentary can do and be, Morris’ epic proves a tragedy of systemic corruption, personal mania, and the inability to grasp that which one knows exists, but remains just out of reach—and how that latter scenario allows the former two circumstances to continue, indefinitely, and at great cost to us all.