Heavy as the human heart and twice as hard, “Una” is a story of sexual abuse that vibrates with the anxious uncertainty of a survivor, a dialogue-driven drama that simmers with the combustible suspense of a Tarantino movie. Adventurously adapted from David Harrower’s Tony-winning “Blackbird” (and boasting a script written by the playwright himself), the film flickers with an intensity worthy of its subject and source material. An agile, vicious piece of work that’s anchored by extraordinary performances from Rooney Mara and Ben Mendelsohn, “Una” maintains its grip even when swinging a bit too hard for the fences.

Una (Mara) is a troubled girl. Introduced as a stranger mounts her from behind in the bathroom of a seedy British nightclub and jackhammers her face into the mirror above the sink, the spindly twenty-something stares at her reflection as though she’s trying to see the color in her eyes. The choreography might suggest otherwise, but there’s no doubt she’s in control of the situation — her partner has found what he’s looking for, but Una is still searching. Stunted and severe, she still lives in her childhood bedroom, still talks to her mother the way a sullen teenager might.

And then — clutching a portrait-sized photograph that’s been freshly ripped out of a newspaper — she steals her mother’s car, drives to a large factory in an industrial town up north, and demands to see a man named Ray (Mendelsohn). Ray, however, isn’t super excited to see her. Shellshocked, is more like it. He drags her down to the company cafeteria, a space so completely surrounded by glass that it feels like an interrogation room that’s been outfitted with windows instead of mirrors.

And that’s where the bombs begin to fall: When Una was 13 and Ray was 40, the two began a technically consensual (but morally dubious and thoroughly illegal) sexual relationship that started at a neighborhood barbecue and ended after a desperate getaway that had the whiff of a kidnapping. It’s been 15 years since the trial, 15 years since they’ve seen each other. Ray has adopted a new name, started a new life and secured the love of a new partner his own age.

For Una, starting over hasn’t been quite so easy. She doesn’t even remember who she was before it happened. She tracks Ray down in search of understanding, or closure, or who knows what. Maybe she wants sex. Maybe she wants violence. Delicately threading the needle between a revenge thriller and a twisted romance, “Una” is such a compelling experience in large part because — without exploiting the trauma of her experience, or that of the real women who are forced to carry her burden — the film recognizes that love and statutory rape may not always be mutually exclusive. The former doesn’t justify the latter, but it certainly has the power to complicate it. The film leans into that idea harder than the play ever could, frequently cutting to Lolita-like flashbacks in which Mendelsohn is paired with the raw and brilliant Ruby Stokes as young Una.

More than 10 years have passed since Harrower first staged the show at the 2005 Edinburgh International Festival, but the Scottish scribe hasn’t been made complacent by his success. Directed by theatre stalwart Benedict Andrews, the big screen version of Harrower’s breakthrough seizes on the potential of its new medium, unpacking a breathlessly tense two-hander into a more full-bodied experience that allows the narrative to spill wider and sink deeper than ever before.

Rooney Mara has a way of making every part she takes feel like the role that she was born to play, but the actress’ gift for impassively conveying some unknown inner turbulence — so essential to films like “Carol” and “The Girl With the Dragon Tattoo” — brings a uniquely rich and volatile immediacy to Una’s buried turmoil. You can feel it under her skin, the steadiness of her sharp features like the calm ocean surface above a shipwreck. The movie only works if you can believe in the truth of Una’s rash and increasingly drastic decisions, and Mara sells us on every one of them, a tightrope walker whose act is all the more exciting because she occasionally loses her balance. She’s been this good before, but she’s never been good quite like this.

Una is not well, and Ray is her disease. Mendelsohn, already having established himself as one of the slipperiest and most dangerously coiled character actors of his generation, tempers his natural caginess with the warmth of a dying fire. His Ray is soft and uncomfortably sympathetic, and Andrews enhances the performance with the intimacy of close-ups — on stage, anyone playing the part had to shout every nuance of the character’s tortured soul so that people in the back row could understand Ray’s conflicted nature, but Mendelsohn is able to ratchet the role down a few notches to a more human volume.

You believe that Ray genuinely cared about Una, which is a necessary first step towards grappling with the bigger question of whether or not that should matter. “You were my neighbor’s daughter, not a target,” he tells his victim, and you believe him. “What could I have possibly given you that wasn’t my body?” she fires back, and you hate him all the same.

But if the story’s newfound intimacy works to its great advantage, the effect of its newfound scale is more of a mixed bag. The background provided by the extended flashbacks results in a rich sense of context, but the foreground shoehorned into the present day portions can feel a bit too clean and contrived for a story defined by its stains (though Andrews makes terrific use of the factory space and its dark corners, forcing his characters to relive their life on the lam as they hide from Ray’s co-workers).

It just so happens that Una has visited Ray on the day of the huge corporate meeting during which he’s supposed to lay off six employees (possibly including Scott, a young worker played by “The Night Of” star Riz Ahmed). It just so happens that, later that same day, Ray is scheduled to co-host a huge garden party with his current wife. But if some of these third act story beats are a bit too much, they clumsily convey a crucial truth: For perpetrators, the fallout from rape — statutory or otherwise — is too often a minor inconvenience. For victims, however, the assaults is a formative moment, resulting in a wound that may never fully heal.

There’s only so much need for male-scripted stories about rape, but Harrower has the presence of mind to know the things he cannot know, and the final moments of “Una” unflinchingly articulate why men should never presume to understand — or dare to downplay — a trauma that women spend a lifetime trying to resolve for themselves. When this ferociously good film cuts to black, that disconnect is left stinging in your ears. “I hate the life that I’ve had,” Una spits at Ray shortly after they first reunite. “I wanted you to know that.” He may not hear her the first time, but one way or another he’ll learn to listen eventually.

“Una” premiered at the 2016 Telluride Film Festival. It is currently seeking U.S. distribution.