How far would you go for a woman who claims with a straight face to be “endeavoring to bring about a change in consciousness through our art?” Not that far, probably: Confronted with that statement, most people would likely make a polite excuse and back away slowly. But most people are not actors, or even aspiring actors, and Sophia Takal‘s eerily askew, drily funny “Act One” thrives — like the character who says those words — on the hunger and anxiety and potential madness of those with an earnest desire to become someone else, before a crowd, for at least a moment in time.

Observing one such person, a highschooler in whom no one else much believes, as she falls into the psychological grip of an acting coach with a very dangerous method, “Act One” is quietly and affectingly plausible until it follows its young protagonist, with pleasingly ripe conviction, off the deep end. At face value, this might all seem quite silly. But the film holds you, in part because stars Ella Beatty and Ari Graynor are so steadfast in their commitment to the bit, and in part because the film isn’t quick to let on what “the bit” actually is. Takal’s approach is unpredictably perched between utter seriousness and high-wire camp; the anonymous stretch of late-’90s American suburbia in which it’s set is recognizable, but feels dreamed, not altogether tethered to reality.

Premiering at Tribeca, “Act One” is Takal’s first film since 2019’s undervalued, Blumhouse-backed “Black Christmas” remake, though it’s far more of a piece with her 2016 sophomore feature “Always Shine” — another unhurried psychodrama that balanced grabby genre tropes with spare chamber-piece intensity. That film eventually swung in an altogether more experimental direction, while this one is more consistent in delivering on its strange promise: Limited theatrical distribution is possible, but it’s likeliest to cultivate an audience via indie-oriented streaming platforms.

Though she’s tall, waterfall-haired and striking, 17-year-old Hannah (Beatty) has the recessive body language of a wallflower: No one’s ever encouraged her to stand out, and even her mother (Elizabeth Reaser) passive-aggressively criticizes her bespectacled appearance. Only when performing on stage does she feel like a bolder, brighter person, so she’s crushed when she fails to secure even a small part in the annual high school play; mom’s suggestion that this is a sign to pursue another vocation doesn’t help.

Considerably more sympathetic to her plight is Melanie Saunders (Graynor), a high-minded acting teacher whose intensive Act One studio Hannah chances upon while researching her favorite young actress, Gracie Thomas (Tavi Gevinson), online. Turns out Gracie studied under her, which is enough to sell the teen on Melanie’s course, despite the sketchiness of the older woman’s résumé. (The film’s amusing period detailing extends to Act One’s clunky website design, not to mention the visual and tonal particulars of turn-of-the-century IM messaging.) One class in, and Hannah is thoroughly seduced both by Melanie’s flattery and by her therapyspeak approach to acting, with its talk of truth-telling and connecting to one’s body. The flirty attentions of handsome fellow student Henry (Nate Mann) — an adult, like everyone else in the class — don’t hurt either.

It doesn’t take long, however, for Melanie’s somewhat controlling mentoring style to take on the aura of cult leadership. By the time she’s urging Hannah to “purge the poison” of her parents’ influence, the flags are looking as red as the ominous, blood-washed fadeouts frequently favored by editors Zach Clark and Matthew L. Weiss, and that’s before she takes an overly hands-on interest in Hannah and Henry’s budding sex life. Graynor, however, plays Melanie with such knowing, unblinking assurance that you can’t altogether blame her naive new protégée for ignoring all the signs. “Act One” is attuned to the enticing adolescent allure of an adult’s yes in a world of no, and if Melanie’s posturing all seems a bit of act, it’s still a persuasive testament to what she professes to teach.

In her first lead following her feature film debut in last year’s “If I Had Legs I’d Kick You,” Beatty (the youngest child of Annette Bening and Warren Beatty) is convincingly guileless as the coltish, unformed protagonist, but there’s a hint of performance within performance here too. That ingenuous quality partially hides a darker, uncompromising drive — interestingly, when Hannah turns it on as a performer, Beatty takes on the more brittly commanding mannerisms of her mother — so she’s up to the melodramatic demands of the film’s ramped-up, smeared-mascara denouement.

As is Takal, clearly having fun with the film’s queasy, lurching atmospherics, abetted by the sparse, shivery, atonal chimes of Jonathan Goldsmith’s score, and the floating, disembodied feel of Robert Leitzell’s camerawork. Not that the filmmaking in “Act One” ever pulls focus from the peculiar magnetism of the performers: They may not be telling the truth, as Melanie insists they must, but they have our attention anyway.