As the crow flies, only about 30 miles separate the port towns of Dover and Calais — a distance that, in many parts of the world, wouldn’t span any greater culture shift than a slight tweak in accent. When those miles are filled with the English Channel, however, opposite coastlines represent opposite worlds, where everything from language to sexual mores are poles apart. It’s a short but jolting journey, an exercise in social and geographic disorientation that British-Pakistani filmmaker Aleem Khan probes to layered, thoughtful effect in his auspicious first feature “After Love.”

Galvanized by Joanna Scanlan’s quiet, searing turn as a white Muslim widow piecing together the separate lives her late husband led on both shores, Khan’s debut confidently blends old-school melodrama with a contemporary political consciousness, suggesting broader, Brexit-era cross-cultural friction while maintaining an intimate domestic focus. Selected for the Critics’ Week program of 2020’s nixed Cannes festival, Khan’s unassuming debut has gone on to robust arthouse success on home turf, sweeping last year’s British Independent Film Awards and scoring a couple of major BAFTA nominations. A North American distributor, however, has yet to step forward for a film that is by no means limited in its cultural resonance to the narrow band of south England and northern France it evocatively explores.

Though “After Love” mints an intriguing career for its young writer-director, already BAFTA-nominated for his short film work, it is equally notable as a belated big-screen breakthrough for Scanlan, a well-regarded character actor best known in the U.K. for her TV comedy work (“Getting On,” “The Thick of It”) and an invaluable supporting presence in such British heritage pictures as “Girl With a Pearl Earring” and “The Invisible Woman.” But she’s never previously been gifted a film lead as demanding as the one she aces here. As Mary, a bereaved Dover homemaker caught between lives lived, imagined and concealed, she brings a grounding emotional conviction to a character whose decisions sometimes come from a soap-opera playbook, and deftly essays the various splintered identities of a white woman committed to the Muslim faith she took up for love, further adrift and incognito as a Briton in France.

After a brief prologue alluding to warm, placid marital contentment, we cut to Mary in the immediate throes of mourning for her husband Ahmed, a ferry captain who spent his days shuttling across the water to Calais and back — routinely sampling a Continental life she’s hitherto been happy to gaze at from the shore. The local Muslim community supports her in her grief, but she prefers isolation; she and Ahmed never had children, and there’s nary a mention of her blood relatives, hinting at painful ties severed over cultural conflicts decades before. This kind of tacit angst is typical of Khan’s lean, precise screenplay, at least in the establishing stages; burning burdens are more vocally unloaded later on.

Yet as the unquestioningly devoted Mary sorts through Ahmed’s effects, fragments of a double life emerge: the identity card of a French woman in his wallet, intimate-sounding voicemails on his phone. Her curiosity leads her across the Channel and to the Calais address of sharp, chic working mom Genevieve (a superb Nathalie Richard). When we meet Genevieve’s biracial son Solomon (Talid Ariss), it becomes clear that her relationship with Ahmed has been a long and storied one. Mistaking Mary, in her modest salwar kameez, for an immigrant cleaner, Genevieve unwittingly lets her love rival into her home. Panicked, Mary goes with the misunderstanding, with all the messy consequences you might expect.

If Khan’s writing never wholly sells us on this key contrivance, “After Love” compensates for this leap with the fine-grained authenticity of its quotidian observation. Many of the film’s most vivid, affecting scenes detail the ordinary business of Mary’s home life and her relationship to religion, performed by Scanlan with intricate attention to physical gesture and routine. We observe her hushed at prayer, but even making roti, handling the dough with palpable tenderness, becomes its own kind of near-spiritual ritual. Khan contrasts this whispery realism, meanwhile, with stark breaks to dissociative fantasy reflecting Mary’s inner turmoil: In her reveries, a ceiling cracks and crashes and floods, and the white cliffs of Dover crumble to powder.

The film’s political commentary likewise emerges in flashes and fissures. The sporadic overlaps and chasms in Marie and Genevieve’s respective experiences point to shared histories of subjugation as women, both with and without children — but also vastly different relationships to cultural and religious mixing, shaped both by national and personal psychology. A queer element to this complex family crisis complicates matters further, in ways teased though not fully explored by a film that already has plenty of conflict, both latent and confrontational, to negotiate. Spare and pared-back in all respects ranging from performance to its clean, airily-lensed aesthetic, “After Love” carries bulky baggage with an elegant lightness, leaving its audience with further unpacking to do.