The title of JT LeRoy is off the mark by only a couple of steps, but they’re gigantic ones. Directed by Justin Kelly, this is the first narrative-fictional treatment of one of history’s most twisty literary hoaxes — so twisty that the word “hoax” is up for dispute (more of that anon). But it’s not primarily the story of JT LeRoy a.k.a. Laura Albert, the one-time-320-pound Brooklyn-raised 30ish woman who passed off her novels as the work of “Jeremiah ‘Terminator’ LeRoy,” a socially-phobic, homeless, transgender (male-born), AIDS-suffering teenage prostitute and son of an abusive truck-stop hooker. It’s the story of Savannah Knoop, Albert’s slim, young sister-in-law, who was pressed to don sunglasses and a Warholish fright wig for magazine photos and public appearances, and who subsequently wrote a memoir called Girl Boy Girl: How I Became JT LeRoy. Knoop’s perspective is interesting — especially when she’s played (very well) by Kristen Stewart. But it’s not that interesting, at least not compared to Albert’s bizarre odyssey. The two documentaries that have explored Albert’s life have viewed her in decisively different ways, the sympathetic one (with Albert’s participation) committed to the notion that Laura effectively became JT, the other opting for a portrait of a manipulative, sadistic fraud. That’s the big story. Mopey, reluctant Savannah has nowhere near the same kind of dramatic stature.

As the film begins (in 2001), Savannah travels to San Francisco and her brother and sister-in-law’s apartment to find the LeRoy ruse already underway, the novel Sarah a success d’estime. Albert (Laura Dern) has developed a host of phone relationships with celebrities like Courtney Love (the only figure from the real story who was sporty enough to appear in the film), Dennis Cooper, Gus Van Sant, et al. Stretched out on the floor, she rasps softly into the phone, spinning tales and prompting intimate confessions. (The movie doesn’t show Albert recording those calls, some of which she allowed director Jeff Feuerzeig to use in his doc Author: The JT LeRoy Story.) Dern is — as you’d expect — wonderful at capturing Laura’s near-erotic thrill at being someone else, someone not-her, and thereby gaining instant access to a whole new kind of relationship. But probably because the real Albert wasn’t involved in this project and owns her own words, the really fascinating transactions happen out of sight and earshot. Instead, we accompany Savannah to her waitressing job. We watch her squirm through a relationship (Kelvin Harrison Jr. is her moralistic lover, given to lines like, “Every time you come back from being JT, you’re a mess”) and fret over a role she fears is beyond her. Savannah remains dully unformed.

Stewart is good at this sort of character, the non-actress who sits outside her own body. And the scenes in which Laura drags Savannah out into the limelight while passing herself off as JT’s friend and minder, “Speedie,” with a gratingly terrible English accent, are a howl. How on Earth did Albert get away with this? (She didn’t, ultimately, but it took a while for the artifice to become outright laughable.) JT LeRoy certainly dramatizes what for Albert was the bitterest irony: that her artistic triumph would also be a confirmation of her own unattractiveness, as she has to watch — like Cyrano de Bergerac — her comely alter-ego take her place in the physical world, the door shutting in her own face. Diane Kruger stands in for Asia Argento as the actress-director who vigorously courted JT to get the rights to make The Heart is Deceitful Above All Things, pulling Savannah away from “Speedie” for some sexually intimate alone time.

I don’t mean to suggest that what happened in the shadows between a famous actress and an awkward but increasingly smitten impostor isn’t lurid and entertaining on its own. It just feels… marginal. The great JT Leroy movie would have this perspective but so much more. Dern’s Laura moons around the truck-stop set of the movie in progress and says that this is her real reality, that JT existed and exists in her in all the ways that matter, but these are signpost lines, only gesturing towards her actressy sense of self and outside the film’s main dramatic line.

JT LeRoy isn’t a bad movie, and with these actresses it’s certainly worth seeing. It’s a passion project for Knoop, who co-wrote the script (songs by her brother, long divorced from Albert, all over the soundtrack) and has been promoting the film. She now identifies as gender-neutral (she uses they/their) and plainly views her life as JT as a turning point in discovering her own identity. But Albert’s cruel words to her (they’re in the movie) after learning that Knoop would be writing a book — “Just because you played a writer doesn’t mean you are one” — resonate in ways that Knoop probably didn’t intend.