Like a cannon blast across the bow of the SS Status Quo, Peter Weir's Master and Commander: The Far Side of the World comes as a thunderous, almost defiant declaration heralding the arrival of a cinematic force to be reckoned with.

Captain “Lucky Jack” Aubrey (Russell Crowe) and Dr. Stephen Maturin (Paul Bettany), the seafaring heroes of Patrick O'Brian's intelligent, thrilling historical novels, materialize in a film as masterful and commanding as the novels themselves.

With 20 volumes published between 1970 and 1999, O'Brian's series about a forceful captain and a refined doctor serving in Nelson's Navy in the days of Napoleon has won a wide and admiring readership. Although great source material is no guarantee of a great film — especially at a time when anachro-nistically up-to-date attitudes, language and behavior are virtually de rigueur for period films — Master and Commander charts a course well removed from the mainstream.

The decision-makers behind most major movies today rely on slavish obeisance to focus groups. The typical marketing strategy aims for the broadest, shallowest-possible appeal across gender, racial and cultural lines. Dumbed-down moral conflicts are painfully spelled out for audiences and “Christian” is shorthand for “psychologically unbalanced.”

How refreshing it is to encounter a film that spurns such condescension and pandering. Master and Commander tells its story with the novels' flawless authenticity and obsessive attention to historical detail. Its characters talk and think and argue like grown-ups — like men of their time and place.

An important part of the film's historical context is its matter-of-fact Christian milieu. In the books, Aubrey is Anglican and Maturin Roman Catholic. Though neither is devout, their Christian heritage remains essential to their identity. This is carried over into the film.

Maturin, an enthusiastic pre-Darwinian naturalist, is fascinated by the varieties of animal life on the Galapagos Islands. As he observes some of the same unusual adaptations that would later inspire Darwin, someone asks whether God changed the animals. “Certainly,” Maturin muses thoughtfully, “but did they also change themselves? That is the question …” There, in two lines, are faith and science — creation and evolution — presented together in harmony.

Later, Aubrey leads the crew in the Our Father and invokes the Christian hope of resurrection as part of a burial at sea. Even in a disturbing episode involving a superstitious rumor of a Jonah-like curse, the film refrains from Christian-bashing.

Master and Commander is also the most technically accomplished seafaring period film ever made, bringing to life with unprecedented vividness the experience of life on the high seas in an 18th-century warship. Here storms are brutal and battles deadly. From the creak of the timbers to the shattering course of a cannonball to the wincing exigencies of naval field surgery, Master never feels less than persuasive.

Crowe (A Beautiful Mind) is, yes, commanding as Jack Aubrey, celebrated captain of HMS Surprise. He succeeds in synthesizing Aubrey's genial charisma and iron-willed leadership, his weaknesses for classical music and stupid jokes, his fondness for his men and his ability to have them flogged or even sent to their deaths when necessary.

The real revelation, though, is Bettany as Maturin. Previously best known for over-the-top roles in A Knight's Tale and A Beautiful Mind, Bettany is astonishingly good in a far more restrained and demanding role. He projects erudite intelligence and sophistication, and makes Maturin's passion for zoology as palpable as Aubrey's love of his ship.

Director Weir (Witness, The Truman Show) hones the story's focus to laser-like intensity. Drawing on the 10th novel in the series, The Far Side of the World, for the central conflict of an extended naval engagement between Aubrey and a larger, more powerful enemy ship, Weir locates the action almost entirely at sea. (In the film's lone concession to marketing expedience, the enemy ship is changed from an American frigate to a French privateer.) There's no obligatory romance, nor even a token female character (though women and romantic elements can be found elsewhere in O'Brian's series).

Instead, Weir focuses on moral and existential issues, especially questions around whether or when moral obligations such as keeping promises or completing one's mission may become contingent upon circumstance. Ironically, as Aubrey and Maturin lock horns, each winds up arguing alternately for a rigorous and an open-ended interpretation of duty. At first, debating the viability of their mission, Aubrey is the rigorist and Maturin the voice of discretion. But later, when Aubrey makes a promise to Maturin on which he later wishes to renege, Maturin is the one insisting on moral rigor. It's Aubrey who ends up pleading circumstantial necessity.

This ambiguity, along with the fact that both characters are sympathetic and likeable, is what elevates these conflicts above so many paint-by-number military-movie clashes (K-19: The Widowmaker, Crimson Tide and so on). It's typical of Weir's even-handedness that, when he raises the theme of power corrupting, he immediately provides a counter-example in the person of Admiral Nelson, the most powerful man in the British Navy. Aubrey has nothing but the utmost respect and admiration for him.

For all its virtues and triumphs, Master and Commander is more about action than ideas. Not that the film is nonstop battle scenes; on the contrary, action junkies are liable to be bored to tears by what passes for hot pursuit in an 18th-century sea battle. Yet Weir maintains tension throughout. It's punctuated with clever bits of strategy and excitement, but only when logical within the circumstance does the pressure boil over into all-out combat.

Although Weir adapts freely, the film is faithful to the spirit of O'Brian's works. Only the most exacting fans will have reason to complain. For those not previously familiar with O'Brian, no cinematic adaptation in recent memory is as likely to make viewers want to go out and get the book. Master and Commander is that good.

Content advisory: Bloody scenes of battle violence and field surgery; a suicide; somewhat profane language; a couple of rude jokes and brief obscenity.

Steven D. Greydanus, editor and chief critic of DecentFilms.com, writes from Bloomfield, New Jersey.