One Day (12A)

Starring: Anne Hathaway, Jim Sturgess, Patricia Clarkson

The best movie romances are seldom smooth or straightforward. Would-be lovers on screen are never as clear-sighted about their compatibility as the audience is. The pleasure (and frustration) of the genre lies in witnessing their faltering attempts at becoming a couple.

One Day, the screen adaptation of the hugely popular novel by David Nicholls, is a romcom that goes beyond genre conventions but still delivers. It is episodic, wildly uneven, and prone to mawkishness. Nonetheless, this is ultimately an effective weepie that shouldn't disappoint the devotees of the book. It is leavened with much of the wry observation about the foibles of the Brits that Danish director Scherfig brought to her earlier UK-set films, Wilbur Wants to Kill Himself and An Education. In its darker moments, One Day also provokes some of the same questions about loneliness, love and fate set by Krzysztof Kieslowski films like Three Colours: Blue, to which it makes passing reference.

You can see why the material appealed to its American backers and its US producer Nina Jacobson (once a very senior executive at Walt Disney). This is the kind of mildly barbed love story that (on the other side of the Atlantic) Nora Ephron might have written a decade ago for Tom Hanks and Meg Ryan. At the same time, the film remains stubbornly British. Nicholls's screenplay has retained the deadpan humour, the in-jokes about British pop and TV culture and that very British sense of nostalgia. (The story opens on St Swithins' Day – 15 July 1988, and ends on the same day in 2011.) The one area where it doesn't probe at all deeply is into lingering British hang-ups about class.

The first encounter between the lovers takes place at dawn after a boozy celebration of graduation day at Edinburgh University. A gauche female student has a drunken one-night stand with a charming but very louche fellow graduate. He's a womaniser: a public schoolboy type with a pronounced narcissistic streak. She is diffident and loyal. They're friends and confidantes who fail to acknowledge their true feelings for one another, even as their lives become intertwined. After their initial fling, they ricochet off in very different career directions and start relationships with the wrong people. So far, so generic.

In advance of the release, there has been much sniping about the suitability of a glamorous American like Anne Hathaway to play Nicholls's heroine Emma Morley, the salt-of-the-earth Yorkshire lass. Hathaway's accent may not be consistent but her performance is nuanced and affecting. Over the 20 year span of the story, we see her transformed from an ungainly ugly duckling in big spectacles into a soulful, worldly-wise gamine with a touch of Audrey Hepburn about her. Right from the outset, Hathaway conveys both her character's longing for Dexter (Jim Sturgess) and her reticence about admitting it. Dexter is charming but relentlessly superficial. He fancies "pretty much everyone". That makes Emma immediately suspicious of his overtures toward her, however much she dotes on him.

Given the central conceit of having the action unfold on the same day every year, it's little surprise that the storytelling is so episodic. We're offered slivers of drama rather than a full and satisfying narrative. Hairstyles and decor change abruptly as does technology. As Scherfig makes clear in rather heavy-handed fashion, in the late 1980s and early 1990s, lovers had to make do with phone boxes to communicate. By 2011, they are only ever a call from a mobile phone away from one another.

During the first half of the film, as Dexter becomes a minor celebrity hosting a late night TV show, his behaviour grows ever more erratic. As his mother (beautifully played by Patricia Clarkson) tells him, "you're not very nice anymore." Emma, meanwhile, is scraping a living as a waitress in a Mexican restaurant. She falls into a dead-end relationship with a would-be comedian (Rafe Spall), who is self-pitying and not very funny at all. At times, the sense of disappointment the characters feel about their lives risks contaminating the film itself. Rachel Portman's overblown score doesn't help.

There's a Two for the Road-style interlude, in which Dexter and Emma venture through France together – and have the predictable misadventures. (They turn up on a nudist beach by mistake. Later, when they go skinny dipping, thieves make off with his clothing.) In his most self-pitying moments, Dexter always reaches out for Emma but then invariably manages to spurn or insult her. Thankfully, Sturgess brings enough charm to his role to make us root for a character who could have seemed wholly obnoxious if played by a less sympathetic actor. Meanwhile, as the years pass, the vignette-style storytelling takes on increasing urgency. We become more aware of the years passing and of the possibilities contracting for the two would-be lovers. There is a sense of foreboding too: a growing suspicion that the fates are against them.

Romantic comedy dramas like One Day are an exercise in tightrope walking. It's equally easy to lapse into sentimentality and morbidity or to lurch too far toward whimsy. Scherfig and her team make some stumbles along the way. Nonetheless, this is a film that becomes increasingly sure-footed the further it progresses. Early on, as years are telescoped into short scenes, it's as if we're watching a series of vaguely interrelated sketches of the characters' changing lives. By the end, though, we're all too aware that each day the couple spend together might be the last.