The Reality of the title is Reality Winner, a National Security Agency contractor who leaked a document regarding Russian hackers seeking to interfere in the 2016 presidential election and was subsequently sentenced to five years in federal prison, the longest sentence ever imposed for that crime. Few Americans probably remember Winner’s case, which in this case is an advantage, better allowing Satter and her star — a revelatory Sydney Sweeney — to work their tautly coiled craftsmanship.

Winner is just getting home from running errands when she’s approached by two FBI agents (Josh Hamilton and Marchánt Davis), who meet her in the driveway and almost immediately begin asking whether there are any animals in the house. Reality’s dog and cat become absurdly comic supporting players in a Kafkaesque chamber piece whose dialogue is taken entirely from transcripts of the ensuing interrogation. Winner — small, blond, a specialist in Dari and Pashto who teaches yoga and owns a pink AR-15, among other firearms — is a bundle of fascinating contradictions: She’s comfortable talking nat-sec shop with the guys and is nothing if not cooperative as more agents gather to search her home, with Hamilton’s special agent Garrick sequestering her in a storeroom to carry out most of his questioning.

Satter’s original title was taken from a brief — and surreal — interruption in Winner’s interrogation; “Reality” is more literal — with its close-ups and wider visual range, the movie becomes an even more compelling portrait of an already compelling subject — and also more layered, as Winner’s story and demeanor morph from wide-eyed naiveté to something more ambiguous. Sweeney, best known for playing cynical Gen-Zers in series like “The White Lotus” and “Euphoria,” delivers a powerhouse performance, stripping every trace of Hollywood glamour to play a 25-year-old Air Force veteran who’s both incredibly strong and breathtakingly vulnerable.

Satter, who makes her filmmaking debut here, brilliantly deploys cinematic technique to deepen and animate what might easily have been a static tableau of talking heads, intercutting real-life tape and introducing moments of static to stand in for redactions in the official record. One of those elisions is the name of the online outlet to which Winner sent the incriminating article. When she says the name out loud, it plays like a whopper of a reveal. As in the recent films “I Carry You With Me” and “You Resemble Me,” Satter melds fact and fiction with meticulous and ultimately stunning results. As a spellbinding example of a new form of docudrama, “Reality” is the kind of movie that demonstrates what cinema can do in the hands of true artists: maybe not change the world, but widen and deepen our understanding of it. “Reality” isn’t just stranger than fiction: It’s subtler, sadder and exponentially more haunting.

TV-MA. Available on Max. Contains some mature thematic elements. 83 minutes.