Nowhere Boy is yet another in the long line of understated British art films that has proved hardy enough (after a year’s delay) to survive the Atlantic crossing. Like so many before, it seeks to charm Americans with green and pleasant landscapes, unrelentingly grey skies, and rough-hewn characters whose salty language and susceptibility to actual human emotions and failings become more adorable as we adjust our ears to a regional accent. This time, we’re treated to a wrenching coming-of-age drama involving a moody, promising Liverpool teenager who is torn between two women locked in a fierce battle for his soul. One is the sturdy (if severe) aunt who has raised him from a boy to walk the straight and narrow; the other is the free-spirited mother who gave him up as a preschooler, but bursts back into his life a decade later to goose his creativity and his rebellion.

The boy just happens to be John Lennon.

But that’s ridiculous, isn’t it? Of course he’s not just John Lennon — he’s an onscreen character (played by Kick-Ass‘s Aaron Johnson) whose future life is one of the most thoroughly explored and well-loved stories of the last century. Nowhere Boy attempts to cross-cut his psyche-shattering family drama with a depiction of the Beatles’ origins, via a blend of imagined scenes and well-documented events – most importantly the Woolton Fete where John met Paul. The fact that such a large segment of the film’s target audience is already familiar with the particulars imposes a certain duality: Can it faithfully tell a tale that’s already known to millions, while simultaneously appealing to moviegoers who aren’t steeped in Beatle lore? (And you thought the only connection between Lennon and Harry Potter was those National Health spectacles…)

Nowhere Boy manages to work on both levels, but only in fits and starts. The key to its success, both as a cinematic character study and as a contribution to the Beatle-biography oeuvre, is its portrayal of John’s mum, Julia – who has always been the most enigmatic personage in the Fabs’ backstory. For Beatles fans, Julia was the ethereal “ocean child” from the White Album, she of the “seashell eyes,” the “windy smile,” and the “hair of floating sky”; later, she was the “Mother” whose abandonment (“you had me, but I never had you”) was famously the climactic linchpin of John’s “Primal Scream” regression therapy.

Here, as written by Matt Greenhalgh (Control) and portrayed brilliantly by Anne-Marie Duff, Julia emerges as a desperate figure — manic-depressive yet attempting to build a normal life from the ashes of her error-strewn past. Duff, heretofore best known to Americans (if at all) for her roles in The Magdalene Sisters, Notes on a Scandal and 2009’s The Last Station, dominates the screen with an intensely emotional performance that careens from high to low with Julia’s bipolarity. Julia’s efforts to become a positive influence for John are perpetually undercut by the quaver in Duff’s voice and the look of terror in her eyes – terror that she will once again succumb to the demons that led her to lose him in the first place.

The film portrays Julia’s relationship with John as fruitful but pathological. She teaches him to play his first instrument, a banjo; it is with her that John first hears “Rocket 88,” often considered the seminal rock ’n’ roll song, and with her that he first sees newsreel footage of Elvis Presley; and she’s the one to whom John turns when trouble is brewing at school, or at home with his Aunt Mimi. However, Julia’s attempts to make up for lost time turn uncomfortable and, for a while at least, verge on incestuous – and eventually both mother and son are devastated as the truth about her abandonment and instability are revealed. Duff’s Julia practically steals the film from its central character; that’s a mixed blessing, at best, even if it’s a satisfying development from the perspective of Beatleologists seeking cinematic documentation of John’s historically crucial neuroses.

Ah, but there’s the rub, to quote another English poet. Our interest in Julia’s fragile psyche, to which we are introduced through imagined scenes, is entirely grounded in what we already know about John The Beatle. Under the tutelage of a first-time commercial-film director, the art photographer and video artist Sam Taylor-Wood, Johnson hits all the well-remembered marks of John’s puckish personality – his creative whimsy, his lack of tact or sentimentality, his defensiveness, his propensity for launching withering insults – without overplaying the role. His performance is less showy than, say, Ian Hart’s as Lennon in Backbeat (1994). Still, it feels authentic … which is, oddly, the most important quality Johnson needed to achieve here. Whether you’re an entrenched Beatlemaniac with full knowledge of John’s history, or merely a casual fan with an understanding of his legendary stature, to some extent we all know what the future holds for this film’s protagonist. And every scene and characterization in Nowhere Boy is inevitably colored by that knowledge, for better and – less frequently — for worse.

On the “worse” side of the ledger is the film’s treatment of John’s stiff-upper-lipped Aunt Mimi, played by Kristin Scott Thomas. It’s a role seemingly custom-made for the actress, who has allowed herself to become one of filmdom’s most typecast performers by playing one character after another pretty much like this one: an ice queen whose frustrating façade appears impenetrable, right up to the moment it is penetrated. The English Patient (ugh), The Horse Whisperer (double-ugh), Random Hearts (triple-ugh), Gosford Park (much better), and more recently I’ve Loved You So Long (luminous!) – by now we know what to expect when Scott Thomas appears on screen, and her Mimi is no different.

Unfortunately, Greenhalgh (who based his script on memoirs by John’s half-sister, Julia Baird) hasn’t given Scott Thomas much to work with. For much of Nowhere Boy Mimi is a caricature, a black-clad (even before her carefree husband dies), unfeeling symbol of austerity and repression against whom teenage John has no choice but to rebel. It is only when John begins to recognize the dark side of Julia’s whimsy that Mimi begins to emerge as a recognizably human character, and she only earns our sympathy after Julia’s tragic death. (Come on! It’s not like this is some huge spoiler – John gave it away himself on “My Mummy’s Dead” in 1970 – though my wife, not an expert in everything Lennon, did gasp and call out, “You’re kidding!” when the car ran Julia down.)

By that point the film has introduced the other key figures of John’s teen years: his boyhood BFF, Pete Shotton, and the rest of the original Quarrymen; a slight, pasty-faced Paul, who is allowed into the band after the aforementioned meet-cute at the Woolton Fete; and Paul’s friend George, who despite his youth can already play a mean guitar lick. Of these, it’s actually Pete (played by Josh Bolt) who leaves the strongest impression on the film. He’s the normal kid swept up in the tempest of John’s oversize personality, the foil for – and often the victim of – Lennon’s legendary prickishness.

That irascible quality occasionally pulls the viewer out of the film, forcing us to think, “Would I care about this asshole if he weren’t growing up to be John Lennon?” Taylor-Wood’s direction doesn’t help; she doesn’t get in the way of her characters, but her telling is rather unimaginative — particularly considering her conceptual-art background, as well as the possibilities offered by John’s stunningly inventive drawings and written musings, which we see here only in passing. It’s intriguing to imagine what an edgier filmmaker like Mike Leigh, who so frequently has forged a gritty humanity from the ill-tempered characters and picturesque urban settings of northern England, could have done with this material.

Still, Nowhere Boy is worthwhile viewing, both for Duff’s riveting performance and for its satisfying depiction of a key chapter in the Lennon/Beatles story. In the latter regard, it nearly meets the standard set by the wonderful Backbeat, which picks up precisely where Nowhere Boy leaves off. Authenticity was, if anything, a bigger issue for Backbeat; it required its actors not only to impersonate characters whose personas were still fresh in the memory, but to re-create small details such as the Beatles’ onstage demeanors (John’s bow-legged stance, George’s little jigs) and the iconic poses from Astrid Kirchherr’s Hamburg photos. In Nowhere Boy, the moments that will make Beatle completists smile are wardrobe-related – costume designer Julian Day has faithfully re-created the outfits worn by John and the Quarrymen in a famous photo from that Woolton Fete, as well as the white-jackets-and-Western-bow-ties look that John, Paul and George sported the first time they were photographed together.

Interestingly, though, the filmmakers found it necessary to put those original photos on screen at the film’s conclusion. Were they flaunting their attention to detail – or were they acknowledging that, in 2010, not so many people have strong memories of those details? Are the Beatles receding from pop-culture monolith to historical artifact? Nowhere Boy‘s dismal box-office receipts to date (on both sides of the Atlantic) offer a hint, but time (and future attempts at portraying Beatledom on screen) will tell. One thing’s for sure, however: If you devoured the Beatles’ Anthology albums and were enraptured by the hauntingly scratchy early recording “In Spite of All the Danger,” you’ll thrill to its use in Nowhere Boy – and you’ll welcome the song fully, at long last, into the canon of Beatles classics. Play the following clip:

One more quick note, as I remain preoccupied with the film’s positing of a borderline-incestuous relationship between John and Julia: During production of Nowhere Boy, Sam Taylor-Wood (then age 41) and Aaron Johnson (then age 18) commenced a romantic relationship; she divorced her art-dealer husband, they became engaged, and in July she gave birth to their daughter. Not that there’s anything wrong with that…