VISIONARY: Zellweger (here with Ewan McGregor) provokes tears without sentimentality.

A film about one of the world’s bestselling children’s books and the ballsy British woman behind it marks the stirring return of Babe director Chris Noonan. We’re talking not Harry Potter but Beatrix (neither my relation), who in 1902 published the palm-sized picture book The Tale of Peter Rabbit to wild popularity. Yet despite the success of the bunny in the blue jacket and, later, 22 other stories of nattily attired critters, not everything was cute and fuzzy in the life of the author/illustrator — an irony made poignantly clear by the nuanced, Kleenex-sopping performance of Renée Zellweger.

In many ways, Zellweger’s Potter evokes her Bridget Jones (though her twitchy mannerisms channel Squirrel Nutkin). An over-30 London singleton with no prospects for marriage, Potter suffers a stifling Victorian existence under the roof of her social-climbing parents (Bill Paterson and Barbara Flynn). Her only “friends” are the wildlife of her watercolors — a bond forged in a lonely yet bucolic childhood, here smoothly depicted in flashbacks that draw on Noonan’s experience with chatty animals and patchwork landscapes. Indeed, Potter chastises and coos to her creations, and through delicate animation they waddle and scamper to life. The risky special effect is at first jarring, even precious, but because Noonan taps it sparingly, such whimsy illuminates Potter’s world view, the depth of her isolation, and in one affecting scene, her emotional and creative turmoil.

Yet A Beautiful Mind meets Doctor Dolittle this is not. (Still, Fur might have been a better title for this bio-pic than for the recent Diane Arbus flick.) Just as all the tut-tutting about Potter’s unmarried status becomes wearying, she falls for her admiring editor, Norman Warne (Ewan McGregor, looking as if he’d jumped off a Smith Bros. cough-drop box). The black sheep of a publishing family, Warne emerges a like-minded, if underdeveloped, rebel. Even greater sparks, however, fly between Potter and Warne’s spunky spinster sister. As played by Emily Watson, Millie Warne is one spirited reason to root for a Boston marriage. Nonetheless, Potter’s fight to love — and to be loved — despite her parents’ condemnation (they believe that tradesmen “carry dust”) intensifies the emotional stakes and compels Zellweger to tone down her usual puffy-cheeked mugging.

Vulnerable yet formidable, even weirdly seductive in her portrayal of Potter’s defrosting passion, Zellweger saves the film from burnished sentimentality. The last half may calculatedly tax the tear ducts, but earlier scenes — such as this aging virgin’s first touch — are more subtly moving. At its best, Noonan’s reverent bio-pic paints Potter as a visionary who poured a life of desolation into her work. At its boldest, she bustles forth as a feminist icon for our times. A devoted naturalist, environmental maverick (she bought up acres of farmland to thwart development), and savvy businesswoman, she does prove curiously relevant. Yet Miss Potter satisfies most when capturing its heroine’s desperate struggle for fulfillment — her conviction that her “little children’s books,” with their exquisite precision and naughty protagonists, were worthy to be embraced as art.