Intimacy divides a young couple in the effective Ian McEwan adaptation On Chesil Beach

Ian McEwan’s 2007 novella On Chesil Beach, about a young couple’s disastrous honeymoon in southern England circa 1962, presents a classic adaptation problem: The book runs less than 40,000 words, the prose largely examines the characters’ interiority, and the majority of the action takes place over the course of an hour in a single hotel room. Without major alterations to the source material, it’s not difficult to imagine the work falling flat on the big screen, even with the assistance of game actors to bring it to life. Confinement doesn’t lend itself to visual spectacle, to say the least.

The film version of On Chesil Beach, penned by McEwan and helmed by first-timer Dominic Cooke, circumvents the problem by employing many, many flashbacks that further explore the couple’s origins. We learn about Florence Ponting (Saoirse Ronan), a classical violinist who dreams of concert halls and protests nuclear proliferation on the side, and Edward Mayhew (Billy Howle), a student of history with a home life marked by restrained chaos due to his mother’s brain damage. They serendipitously meet and quickly fall in love. There are some differences between them, some major (he’s middle class, she’s aristocratic) and others minor (he likes Chuck Berry, she worships Beethoven), but it’s nothing that they can’t conquer with wide-eyed idealism and a romantic spark. It’s only when they’re awkwardly staring down the prospect of consummation that their respective fears meld into a collective state of trepidation and, quickly, outright panic.

McEwan’s use of flashbacks has a two-pronged effect. First, they build out Florence and Edward’s relationship so that their eventual fallout has dramatic weight; second, they draw out the inevitable moment when things go horribly wrong. The former is ultimately more effective than the latter, an unintentionally comical choice that will likely prompt audiences to adopt their best Monty Python impression and yell, “Get on with it!” McEwan’s screenplay excels at crafting small gestures that have existential import—an unexpected smile from a stranger, a doting father’s solemn expression, an improvised meal with a new family—and Ronan and Howle, though he palpably struggles to keep up with his scene partner at times, meet the material at eye level. They imbue their characters’ adolescent courtship with genuine feeling, and it goes a long way to overcoming the ordinariness of it all. Cooke mostly acquits himself by deferring to his actors, and cinematographer Sean Bobbitt adds a nostalgic sheen to the proceedings. It’s all very English, and McEwan goes to lengths to convey the culture’s conservative social mores at the time, and how they inform Edward and Florence’s approach to marriage and sex.

Then, of course, there’s the incident that the film builds to for most of its runtime. It’s a risky gambit to depict on screen (without giving much away, it involves Edward’s sexual inexperience and Florence’s discomfort with the mere idea of intercourse), and, frankly, the way Ronan and Howle play the scene feels much campier than intended. But though the moment itself might feel overblown, On Chesil Beach invests the fallout with so much honest consequence that it’s difficult not to take it seriously. Immaturity and cultural repression conspire to turn an otherwise uncomfortable episode into a fork-in-the-road choice that has lingering lifelong effects. It helps that the two leads are so engaged with their characters’ own worldviews that neither comes across as “wrong” in their fight: Ronan turns what could have been a simple prude in the hands of a lesser actor into a strong young woman with staunch principles that even she doesn’t fully understand; Howle admirably fills Edward with youthful frustration that never once feels grating or affected. On Chesil Beach is a minor story by design, one that uses a lovers’ quarrel to interrogate evolving social values, but sometimes it’s the most minor stories that contain some of the most overlooked ideas.