Faithful lovers and filmmakers

Ian McEwan, one of Britain’s most accomplished novelists, has been in the habit of showing his books to his wife as soon as they’re completed. When she finished reading “Atonement,� she did something unprecedented: She cried. That, McEwan has said, is when he knew he’d written something special. Which he had.

An assured and deeply moving work, “Atonement� is at once one of the most affecting of contemporary love stories and a potent meditation on the power of fiction to destroy and create, to divide and possibly heal. It is the kind of novel that doesn’t get written very often or, if it does, rarely gets transferred to the screen with the kind of intensity and fidelity we find here.

For, as directed by Joe Wright from Christopher Hampton’s adroit script and acted with fervor by Keira Knightley and James McAvoy, this is one of the few adaptations that gives a splendid novel the film it deserves.

A rich, old-fashioned love story spun out of modern psychology and postmodern storytelling, this film’s decades-long, war-torn examination of love, pain, betrayal and, yes, atonement has the kind of expansive sweep that brings “The English Patient� to mind. It’s a film of layers and surprises, not the least of which is realizing that director Wright’s robust style is more suited to this film’s source material than it was his last time around.

For though “Pride & Prejudice,� which also starred Knightley, was generally applauded, Wright’s vigorous insistence on infusing the strongest possible emotions into his films rode roughshod over and half-destroyed Jane Austen’s quite different sensibility.

McEwan’s richly expressive “Atonement,� however, is a different animal, resilient enough to draw strength from Wright’s vivid techniques. And the director’s decision to stick closely to the book, to allow the weight of McEwan’s choices to guide him at critical junctures, is a key factor in the film’s success.

This is especially true in “Atonement’s� opening segment, set in an enormous country estate on the hottest of summer days in the England of 1935, a country doing its best to avoid the realization that it is on the verge of total war.

Sounds, like the buzzing of flies, are important in creating a feeling of exhausting languor, but the first thing we hear is insistent typing. Thirteen-year-old Briony Tallis (an exceptional Saoirse Ronan) is finishing a play. One of those willful children, in McEwan’s phrase, “possessed by a desire to have the world just so,� she is intent on staging her work even though no one else in the huge house, including her exhausted mother and her fidgety trio of visiting cousins, really cares.

Equally indifferent are Briony’s older siblings. Her brother Leon, for instance, is more interested in showing off the friend he is bringing back from college, the chocolate heir Paul Marshall (Benedict Cumberbatch, memorable as William Pitt in “Amazing Grace�).

Briony’s sister Cecilia (Knightley) is also caught up in dramas of her own. A classic oh-so-bored bright young thing, rail thin but glam in Jacqueline Durran’s beautiful costumes, Cecilia is at Cambridge with Robbie Turner (McAvoy), the son of the family housekeeper who’s there on a scholarship provided by her father. They move in different circles at university, but there is a potent kind of feeling between them that makes both of them nervous and uncertain.

At these early stages of the film, something happens between Cecilia and Robbie that is so important we see it twice. First we watch it through Briony’s eyes, as, unseen, she witnesses the event through an upstairs window of the house. Then we go down to ground level and get to understand what actually took place.

We see these pivotal events twice to underline one of “Atonement’s� key dynamics. As terribly sure of herself as only a headstrong 13-year-old can be, Briony thinks she knows what she’s seen, but she has fatally misconstrued the incident. That leads with terrifying rapidity to another misapprehension, which in turn triggers a series of devastating situations that enmesh all the key characters and take decades to fully play out.

I’m being noticeably reticent about what Briony saw and what it led to, and there’s a reason. Though it is very modern in its language and psychological complexity, “Atonement� makes masterful use of the contrivances of melodrama to tell its story and make its points. This is a film, like the novel, that benefits more than usual by being experienced with as little previous knowledge as possible of precisely where it is going.

To put a story like this across, the actors must be in complete sync with the project and each other, and McAvoy, recently seen opposite Forest Whitaker in “The Last King of Scotland,� and Knightley, whom the “Pirates of the Caribbean� movies turned into an international star, are able to do just that.

These performers not only have the looks for a sweeping love story, they also have the skill to throw themselves into the proceedings like they really mean it. The supporting cast, especially young Ms. Ronan, Romola Garai and Vanessa Redgrave, easily come up to the same standard.

And though “Atonement� is only director Wright’s second theatrical feature (he’s done TV work in Britain), he has a veteran production team (including cinematographer Seamus McGarvey, production designer Sarah Greenwood and editor Paul Tothill) that makes the film’s rich pictorialism possible and also easily handles bravura moments like a five-plus-minute single shot showing the World War II evacuation scene at Dunkirk.

Like the best of titles, the full meaning of “Atonement� is only clear at its conclusion. You may think you know what its referring to, but until you come to the end, you really don’t. It’s that kind of a novel and, thankfully, that kind of a film.

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“Atonement.� MPAA rating: R for disturbing war images, language and some sexuality. Running time: 2 hours, 3 minutes. In limited release.