Eddie Redmayne smooths some of Stephen Hawking’s rough edges, but the physicist grows more demanding as the film and his illness progress. (Liam Daniel/Focus Features)

Although the awards race officially gets started in early September, when spiffed-up contenders make their debuts in film festivals from Venice to Telluride to Toronto, Academy Award season doesn’t get underway in earnest until the polished, anthemic biopics start showing up in theaters. “The Theory of Everything,” a stirring if conveniently cosmeticized portrait of physicist Stephen Hawking and his wife, Jane, is such a classic example of Oscar bait that it might as well have arrived with a subtitle attached: “And They’re Off!” To its credit, though, this handsome, ultimately very moving drama winds up subtly upending as many genre conventions as it obeys.

Based on Jane Hawking’s memoir “Travelling to Infinity: My Life With Stephen,” “The Theory of Everything” doesn’t dwell too long on Hawking’s most famous intellectual achievements; for brainy disquisitions on space-time singularities and black holes, there’s always “Interstellar,” which derives scientific footing from the work of Hawking’s colleague Kip Thorne. Rather than a “Beautiful Mind”-ish portrait of a thinker battling disability, filmmaker James Marsh has created a spirited, affecting meditation on marriage, specifically how Hawking’s affliction with a brutally degenerative disease and Jane’s mostly unflinching support and motivation throughout its worst predations resulted in a relationship that, while far from ideal, bears celebrating, if not emulating entirely.

“The Theory of Everything” begins in the early 1960s, when Hawking — played by Eddie Redmayne — is a graduate student at the University of Cambridge, and when he meets Jane (Felicity Jones), who’s studying medieval Spanish poetry. Gawky and bespectacled, full of stumbles and fumbles, Hawking takes a severe fall one day and can’t get up: Soon thereafter, he’s diagnosed with amyotrophic lateral sclerosis and told he has two years to live. After Hawking descends into an understandable depression, Jane shows up to insist that he snap out of it. The two begin to date despite the fact that she’s a devout Christian (Church of England) and he’s an outspoken atheist who has just “a slight problem with the celestial dictator premise.” (When Stephen asks Jane out on a Sunday morning and she delicately tells him she’s usually busy then, he immediately twigs that he has a formidable rival. “Oh,” he responds knowingly. “Him.”)

Directed with graceful vibrancy by Marsh from a script by Anthony McCarten, “The Theory of Everything” initially has all the markings of the kind of valorizing cine-biography of the safest, most conventional kind. Redmayne, submerging his fashion-model looks under a performance of remarkable physical and facial contortion, lends winsome charm to a character who, in real life, has often been described as prickly and difficult. And there’s no doubt that the filmmakers have smoothed out some of the most problematic contours of the Hawkings’ marriage — which ended in 1995 — in the name of all-important audience “relatability.” (The fact that Hawking comes off so sympathetically in the film might explain why he allowed his real-life mechanized voice to be used in the film after Redmayne’s character receives a tracheotomy in 1985.)

But even with those liberties,“The Theory of Everything” succeeds as something deeper and more complex than facile great-man portraiture. Although Redmayne’s vulnerable impishness and playful charm virtually erase Hawking’s real-life shortcomings, they’re still evident, especially when, as he grows more and more dependent on Jane, his demands begin to seem increasingly peevish and cruel. Redmayne is understandably getting most of the accolades for an excruciatingly demanding physical performance that also manages to be surprising expressive. But Jones deserves just as much credit for her less showy but more technically tricky portrayal of a woman who, far from being a traditional self-sacrificing helpmate, is trying to reconcile her Christian conscience and conjugal devotion with her own academic career and evolving physical and spiritual needs.

At its best, “The Theory of Everything” portrays its central love story not as the stuff of soap-opera melodrama or zero-sum ultimatums, but as a relationship between recognizably imperfect adults, fraught with many familiar complications, contingencies, flaws and fatal setbacks. Marsh, best known for his sublime 2008 documentary “Man on Wire” and making his narrative feature debut here, evinces the same penchant for delicacy and lyricism during the denouement of the Hawkings’ marriage as he does during the idyllic first days of their romance. A stunning third-act sequence, when the director briefly sets the characters free from the literalness that binds them, isn’t just a bold visual move, but elevates the story that’s gone before. “The Theory of Everything” achieves its uplift by acknowledging that uplift isn’t always possible, at least in the strictest sense: It’s an exceptional film, not because of its protagonists’ impressive triumphs, but because it honors their struggle.

★ ★ ★

PG-13. At area theaters. Contains thematic elements and some suggestive material.
123 minutes.