To hear Mary (Ella Bruccoleri) tell it, she is no one special. She is not “the beautiful one” of her sisters, nor “the quick-witted one,” and she is certainly not “the ones who are good at games and full of youthful energy.” If she is anything, she is the odd duck, seemingly doomed to a future of getting overlooked by suitors and dismissed by her family.

It is both ironic and entirely appropriate, then, that this very ordinariness is precisely what makes her such a striking heroine in The Other Bennet Sister, BritBox’s wildly charming effort to reframe the resident frump of Pride & Prejudice. With its refreshingly grounded tone, generous sense of empathy and, above all, absolutely marvelous lead, the series pulls off the neat trick of convincingly expanding on Jane Austen while standing proudly on its own two feet.

Like Mary, however, the series (adapted by Sarah Quintrell from the novel by Janice Hadlow) takes time to come fully into itself. Its opening chapters are a dutiful retelling of the events from Austen’s classic, this time from Mary’s perspective.

So while Elizabeth (Poppy Gilbert) meets Darcy (Victor Pilard) at the ball, we’re off with Mary on the sidelines, hoping against hope she’ll be asked to dance. When Elizabeth rejects Collins (Ryan Sampson), we hear the news as she does — secondhand from her gossipy younger sisters (Molly Wright’s Kitty and Grace Hogg-Robinson’s Lydia). And while the rest of the Bennet girls go off one by one into wedded bliss, we remain stuck at home with Mary, her hypercritical mother (Ruth Jones) and disengaged father (Richard E. Grant).

It could all be rather tedious, if not for two things. One is Mary’s narration, matter-of-fact but subtly funny and judiciously deployed, which helps to establish who this unconventional young woman is even before Mary herself seems to know. The other is the show’s brisk pacing. The end of the second episode marks the end of familiar territory, as a jolt of fate sends Mary to stay with her aunt (a very likable Indira Varma) and uncle (Richard Coyle) in London. From that point on, the remaining eight half-hours episodes represent completely uncharted waters.

Well — mostly uncharted waters, anyway. Like its parent story, The Other Bennet Sister is very much concerned with the attracting, rejecting and/or accepting of potential suitors, here including a charismatic bon vivant named Mr Ryder (The Girlfriend’s Laurie Davidson) and a sensitive lawyer named Mr Heyward (Dónal Finn). And despite Mary’s insistences, in voiceover, that her romantic fate is “almost beside the point,” the series puts far more shading into her flirtations than it does non-romantic connections like her fast friendship with the clever Ann Baxter (Varada Sethu).

But The Other Bennet Sister does successfully frame Mary’s love life as subordinate to the much richer and more rewarding story of her self-actualization. If Austen-inspired works have frequently taken inspiration from unforgivingly hierarchical milieus like high school or the gay party scene, Mary’s saga might be the subgenre’s version of a going-to-college story, in which a lifelong misfit gets a chance at reinvention. Away for the first time from the sisters who’ve always overshadowed her and the mother who’s never appreciated her, and encouraged by the guidance of her endlessly patient aunt, Mary blossoms from a painfully insecure wallflower into an independent-minded young woman.

Her road there is not without some minor missteps. On Mary’s part, those include some garish dresses that (in a smart bit of costuming by Sian Jenkins) speak to both Mary’s newfound boldness and her clumsiness in wielding it, as well as some bruising interactions with the hilariously bitchy Caroline Bingley (Tanya Reynolds). On the show’s, it includes a portrayal of Mrs. Bennet so cartoonishly unpleasant that even the last-ditch effort to deepen her lands with a thud, and a couple cheesy moments that lean too far into fan service. (Is it even a Regency romance if a handsome man in a white shirt isn’t getting drenched?)

But those are tiny quibbles about a series that otherwise demonstrates an impressive command of tone, pacing and (most crucially of all) characterization. As Mary finds her footing as a governess to the Gardiners, as she visits new places and meets new people, as she starts to see a future for herself beyond the “marriage or misery” dichotomy drilled into her all her life, she becomes more the guileless, bookish nerd we met at the start, not less. The difference is that, increasingly freed of the insecurities and anxieties holding her back, she starts to embrace those qualities as gifts, not flaws.

Bruccoleri’s precision-cut lead turn is an absolute boon in this regard. “You lack artifice. Your qualities shine out. They’re not corrupted by the false polish of the world,” an admirer marvels at one point, and though he’s talking about Mary, he could just as well be describing Bruccoleri’s fantastically dynamic performance. At a time when so many series seem engineered with the assumption that inattentive viewers require every nuance spelled out for them, Bruccoleri invites you to lean in for close study. Putting her face through a million tiny expressions in the space of a sigh, conveying volumes of complicated emotion just through the way she adjusts her glasses, she’s never less than a thrill to watch.

If there’s a downside to this emphasis on thoughtful self-discovery over such “fripperies” as balls and proposals, it’s that at some point I felt myself bracing for the show’s inevitable recursion to Regency romance tropes. By the time it got there, though, I couldn’t find it in me to be disappointed — not when the series had so thoroughly won me over to Mary and her wishes. That The Other Bennet Sister delivers as both a love story and a coming-of-age journey makes it a treat. That it manages to do so in entirely its own way, sacrificing none of its unique spirit in the process, makes it indelible.