The Tale” opens with a warning: “The story you’re about to see is true … as far as I know.”

What follows is a painstaking, wrenching examination into exploring what’s “true” and what’s not, what’s imagined and what’s real, the stories we create in order to protect ourselves from the potential wreckage that lies dormant inside us. As written and directed by documentarian Jennifer Fox from her own experiences, “The Tale” follows Jenny (Laura Dern) as she reevaluates the first “relationship” she had with an adult man when she was just 13 years old. Disoriented, she weaves in and out of her own experiences, determined to understand a past she that she’s been revising all her life.

Jenny’s deep dive into herself starts after her horrified mother (Ellen Burstyn) finds a story that 13-year-old Jenny wrote after spending a summer with running coach Bill (Jason Ritter) and equestrian expert Mrs. G (Elizabeth Debicki). While her mother insists that the story proves that Bill abused her under Mrs. G’s watchful eye, Jenny herself can’t accept that version. She had always told herself — and anyone who asked about her sexual firsts — that she had had a relationship with “an older man.” She’ll acknowledge that though Bill was pushing 40 while she was a teen wasn’t ideal, but hey, it was the ’70s. Everyone has some story like hers….right?

What finally convinces her that she’s wrong comes with one of the film’s most effective and jarring sequences. She finds a picture of herself at 13 and realizes that her image of that summer was awry: She wasn’t a lanky teen on the cusp of adulthood when Mrs. G groomed her, when she lost her virginity to Bill. She was a prepubescent child who soaked up their attention like a sapling desperate for nourishment.

She was a child.

To be clear: it would be rape whether Jenny was 15 or 13 years old. But “The Tale” makes that crucial moment when Jenny realizes just how young she was land hard by swiftly swapping out the older actor playing her in the initial flashbacks (Jessica Sarah Flaum) for a startlingly younger one (a heartbreaking Isabelle Nélisse). It’s a brilliant device, not least because it underlines just how warped most onscreen depictions of teenagers are when they’re so often played by actors older than their characters.

And so Jenny replays her own memories back to herself, this time starring a more accurate image of herself — one that shakes her to the core. Equally desperate and terrified to understand what happened, Jenny forces herself to investigate her story like she would any other. Dern and Nélisse, performing shadows of each other, trade narrating duties as Jenny struggles to reconcile the version of her life she had been telling herself with the life she actually lived.

Jenny’s perception may be hazy, but Fox’s directing and script are so purposeful and direct that it can be very hard to watch “The Tale” without having to look away. Actors make eye contact with the camera to show us these vaunted figures in Jenny’s memory from her perspective. Adult Jenny conducts mock interviews Bill, Mrs. G., and herself, asking them the pressing “why” and “how” questions that none of them can truly answer. The first time Bill rapes her, Fox shows it from Jenny’s point of view, the memory becoming terrible, claustrophobic, suffocating.

This is extraordinarily tricky material, but the cast performing it is up to the challenge. Burstyn finds both anger and sadness as her character comes to terms with what she did and didn’t know; Common doesn’t have quite as much to work with as Jenny’s current partner, but acquits himself well nonetheless. In flashbacks, Debicki plays Mrs. G as an effortlessly towering figure that makes it easy to understand why Jenny would want to impress her so badly, and Ritter uses his inherent warmth to chilling effect in order to show how abusers reel in their prey. In the present day, Frances Conroy plays Mrs. G as shockingly shrunken and lost, while John Heard’s Bill tries to chuckle away his sinister past.

And while the interplay between Dern and Nélisse occasionally relies too hard on clunky voiceover, both are so good at acting different parts of the same person that them coming together by the end feels entirely natural. Dern, as always, finds a way to take on a difficult role that reveals its nuances. Her Jenny is angry, heartbroken, hesitant, and blunt all at once — a seemingly paradoxical combination that many survivors will recognize in themselves.

When “The Tale” premiered at this year’s Sundance Film Festival, it was lauded as one of the first great films to tackle the #MeToo era. It’s true that watching Jenny dig through her own past in order to understand her own trauma — not to mention the looming fact that her abuser didn’t begin and end his cycles of abuse with her — feels uniquely relevant now. But not only did Fox begin the process of making this film a decade ago, but people have been working through and creating art about their trauma forever. Abuse of power isn’t new, and as Fox’s film insists, neither are stories like Jenny’s. The difference now is that more people are listening.

Fox says she wrote and directed “The Tale” for the same reason that her onscreen facsimile delves into her past: to reveal and understand the truth. But “The Tale,” to its immense credit, never pretends that “the truth” that Jenny seeks is some clear destination she could find if only she had the right roadmap. Instead, it shows that finding the truth of any story is finding the strength to see it clearly.

TV Review: “The Tale” on HBO

Made for TV movie; HBO, 10 p.m. Saturday May 26. 1 hour and 54 minutes

CREW: Producers Jennifer Fox, Oren Moverman, Laura Rister, Mynette Louie, Simone Pero, Lawrence Inglee, Sol Bondy, Regina K. Scully, Lynda Weinman and Reka Posta.

CAST: Laura Dern, Isabelle Nélisse, Elizabeth Debicki, Jason Ritter, Frances Conroy And John Heard, Common, and Ellen Burstyn