Liberal Arts, Josh Radnor, 97mins (12A)

Love letters straight from the arts

Mind the age gap: Josh Radnor romances Elizabeth Olsen in 'Liberal Arts'

Anyone who looks back on their college days and thinks it was bliss to be alive in that dawn should definitely make time for Liberal Arts, a bittersweet comedy of manners that pitches age against youth and reveals it as an unequal contest. The film pays nostalgia its due, while admitting that it's possibly not the healthiest basis on which to live your life – you can get a crick in your neck from all that looking back.

Josh Radnor, who writes and directs the film, knows that a problem with the past is to "romanticise it out of all proportion". They happen to be the very words Woody Allen uses in his opening voiceover in Manhattan (1979) – he was talking about the city, but there are strong echoes here of both that film and its maker, a nostalgist if ever there was. Radnor plays Jesse Fisher, a bookish New Yorker who's found that the grace and joy of his Midwest college years have not been matched in the adult world of work (he's a university admissions officer). Jesse's on a downward swing – he's just split up from his girlfriend, and lost all his clothes to a laundromat thief – so when his favourite college professor invites him to his retirement dinner, he jumps at the chance of a return to his old stamping ground.

And as soon as he's back among the manicured lawns and leafy pathways he knows how much he's missed it. (The film is shot in Kenyon College, Ohio, which was Radnor's own alma mater.) The beloved prof, Peter (Richard Jenkins), introduces Jesse over dinner to two old friends and their daughter Zibby (Elizabeth Olsen), whom he takes to at once. She's a drama student in her second year, and when they run into one another again the next day she tells him, "I think my mom had a little crush on you."

Jesse's face falls, but no, it's fine, Zibby proves to have a little crush on him, too, and before he heads back to New York she asks him to correspond, old-school, with paper and pen. Talk about nostalgia. The letters they send mostly concern their shared love of classical music, though between the lines of their epistolary chat about Mozart and Massenet we feel the pressure of what might happen between them, or what they think might happen. Eventually, Zibby writes asking him to visit, and off he goes.

Gathering towards romance, the film first creates a false impediment, about literary taste. She's just devoured a certain vampire trilogy and loved it; he thinks it's the worst book he's ever read. But we all know that the actual impediment here is "age-appropriateness". He's 35, she's 19, a discrepancy of 16 years, which naturally causes him more anxiety than it does her. "I can't work out if it's that you're advanced, or that I'm a little stunted," Jesse muses. One is reminded again of Manhattan, and Woody Allen's romance with the young Mariel Hemingway: he was 42, she was 17, though you may remember that Allen was worried not about any potential creepiness but that the cops might break in at any moment.

The other difference is that Radnor and Olsen don't look that distant in age, whereas Woody Allen has always seemed old, and his cosying up to Mariel could not quite prevent an inward feeling of "eeew" (multiplied tenfold when he took leave to kiss Julia Roberts – age gap: 32 years – in Everyone Says I Love You).

For Jesse it's also complicated by the sadness that he's back where he doesn't really belong – college – and among people prepared to tell him so. Peter, who's hit the wall of his own midlife crisis, admits he still feels he's 19 inside. "Nobody feels like an adult. It's the world's dirty secret." An encounter with another professor, Judith (Allison Janney), whose Romantic poetry classes he used to love, pours even colder water on Jesse's hopes of reconnection. So must disillusionment come with age? Radnor suggests that it doesn't have to, that, on the contrary, "grace is neither time- nor place-dependent" – you just need the right books and the right music. The film can get a little winsome about this, notably in the friendship Jesse strikes up with a depressive English student (John Magaro) who drags round a copy of David Foster Wallace's magnum opus Infinite Jest like a comfort blanket. And Zac Efron, who pops up as a sort of campus Puck, is a bit annoying with his Peruvian knit-cap and his bland "everything is OK" philosophising.

What elevates and enhances the film is the casting of the two leads. Those, like me, who've never seen Josh Radnor or his US sitcom (How I Met Your Mother) may be at an advantage; his hesitant manner and slight hint of Johnny Depp around the mouth are charming on this first acquaintance. Elizabeth Olsen, who gave one of the freshest performances of the year in Martha Marcy May Marlene, is again a wonder of naturalism as Zibby. The disarming straightness of her gaze and her easy laugh are at once girlish and completely grown-up: you can see why Jesse was confused. I'm not sure about the film's reasoning that books, for all their pleasure and instruction, get in the way of life. That is to mistake reading as an adjunct of life, something done in your spare time, whereas it's really an inextricable part of it, like breathing and eating. Nineteen-year-olds may not understand this, and maybe not 35-year-olds either, but one day they will.