“The Samurai and the Prisoner,” the latest film by the Japanese director Kiyoshi Kurosawa, is a quadruple-decker historical mystery so fiendishly complicated that even its title constitutes something of a red herring. The picture begins in 1578, during Japan’s Sengoku (or “warring states”) period. One stronghold after another has fallen to the ruthless conqueror Nobunaga Oda—often celebrated as the first great unifier of Japan but here cast as a largely offscreen mega-villain. The wise and formidable warlord Murashige Araki (Masahiro Motoki), a former ally of Oda’s, has made the shocking, seemingly suicidal decision to turn against him. Now an Oda envoy and renowned strategist named Kanbei Kuroda (Masaki Suda) has come to Murashige’s fortress to convince him that resistance is futile. Refusing to surrender, Murashige has Kanbei thrown into a dungeon—a breach of the samurai code of honor, Kanbei protests, insisting on being either released or executed. With the castle surrounded by Oda’s forces, Murashige, too, can feel the walls closing in. For the rest of the movie, these two brilliant men will remain locked in together, samurai and prisoners both.

The film, which Kurosawa adapted from a 2021 novel by Honobu Yonezawa, is both a methodically paced chronicle of a nearly yearlong siege and an elegantly constructed puzzle box, divided into four compartments, or acts. Each act unfolds over a season, and each season brings with it a devilish new conundrum. Corpses are not a rarity in civil war, but only a few of the bodies that turn up here have been cut down in the heat of battle; instead, in the manner of detective fiction, they are casualties of a sinister and calculating higher intelligence, which seems to be operating under the guises of multiple murderers. It’s winter when the story loses its first and most upsetting victim: the young son of a warlord who recently surrendered to Oda. Some call this divine punishment for his father’s treachery. The circumstances of the boy’s death—an arrow appears to have been shot through a narrow opening between latticed sliding doors—are indeed confounding enough to suggest supernatural intervention. (Yonezawa’s novel may be a Japanese feudal-era companion to Umberto Eco’s “The Name of the Rose,” but the lethal logistics here also reminded me of “The Judas Window,” one of the greatest of John Dickson Carr’s celebrated locked-room whodunnits.)

Kurosawa’s film is awash in such grim mayhem, but the filmmaking itself feels serenely unbothered. The movie is, like any real investigation, a drawn-out and loquacious affair, with thickets of dialogue that—for all the historical and militaristic context that Kurosawa has deftly elided from Yonezawa’s novel—can be as dense as the plotting. With one notable exception, the murders are never depicted in progress; they’re revealed to us in the past tense, as seasonal problems waiting to be solved. In the spring, two rival clans, both fighting under Murashige’s command, try to claim credit for slaying and decapitating an enemy general—a riddle that becomes all the more perplexing when the trophy head is unexpectedly (magically?) disfigured. In the summer, the bodies of a prized warrior and a priest are found in close proximity—a double homicide that may also have been a robbery. The finale, set in autumn, concerns an accident of nature—a warrior is struck by lightning, in full view of Murashige and his other men—that turns out not to have been so accidental. At a certain point, the deadly seriousness of so many consecutive anti-miracles can’t help but turn faintly comical. How much divine punishment can one fortress take?

Murashige, though hardly a mental slouch, is stymied by these events, and with each new case he winds up turning to Kanbei’s superior tactical mind for help. The prisoner thus becomes the detective, albeit with shackles and a straw mat in lieu of an armchair, and Suda, the star of Kurosawa’s gripping recent thriller “Cloud,” inflects his otherwise cool, clammy performance with wild flickers of genius and menace. Kanbei isn’t exactly Hannibal Lecter, and Murashige, whom Motoki lends immense stature, wisdom, and gravity, is no one’s idea of Clarice Starling. But Kurosawa, who came to international prominence in the late nineteen-nineties with the brilliantly unnerving serial-killer film “Cure,” nonetheless finds a sneaky “Silence of the Lambs”-adjacent pleasure in his characters’ deductive rapport. Yonezawa’s novel gives him the chance to splice his procedural DNA into the unlikely host cell of the historical drama—the first historical drama, as it happens, that he has ever directed.

Did Kurosawa, who has made dozens of features in the past four decades, steer clear of Japan’s feudal era until now so as to avoid comparisons with his more famous namesake—the one who directed such samurai classics as “Throne of Blood,” “Yojimbo,” “The Hidden Fortress,” and, of course, “Seven Samurai”? It’s more likely, I think, that the younger Kurosawa was simply waiting for the ideal vehicle to come along, one that would allow him to slyly turn some of the conventions of the war picture inside out. Battlefield carnage is kept to a minimum, and the action unfolds, with almost perverse austerity, in private rooms, enclosed courtyards, and one dimly lit dungeon. Yonezawa’s novel allows Kurosawa to do what he has always done best: track down killers, investigate lovingly detailed crime scenes, and apply the mechanics of murder plots toward gravely existential ends.

In “Cure,” a hellish riff on Agatha Christie’s “Curtain,” Kurosawa concocted a gloomy tour de force of social alienation and spiritual dread, using a series of inexplicable killings to suggest a terrifying void in the fabric of modern life. “The Samurai and the Prisoner” may be set centuries earlier, but it’s a Kurosawa movie through and through. The talk is grave, the editing unhurried; the camera holds multiple characters in the frame and watches them from a sedate remove. The murders and their ensuing investigations have a genuine philosophical density, and Kurosawa uses them to interrogate the mores of the era: the implications of the samurai code, the horrors of war, the nature of individual will, the meaning of courage, and, perhaps most of all, the uses and abuses of religion.

Divine punishment can make for great spectacle, and spectacle, the film argues, can easily become an instrument of mass manipulation and mind control. One of its animating tensions is a clash between old traditions and beliefs and recent encroachments, including Christianity. (The first Jesuit missionary in Japan arrived in 1549.) This conflict erupts into the open when a local Christian church suddenly goes up in flames. The implications of this struggle seem to weigh with particular heaviness on Murashige’s wife, Chiyoho (Yuriko Yoshitaka), a devout Buddhist, who, in one mesmerizing sequence, deconstructs an oft-repeated aphorism: “Advance to Paradise, retreat to Hell.” What this means is open to interpretation, but it is wielded here primarily as a slogan of battlefield aggression—a rallying cry for soldiers who have been trained to abandon their fears, push bravely onward, and embrace a glorious death.

Murashige, who has killed many men in battle, no longer has much use for that glory. Among warlords, he has become an unfashionable pacifist, and his refusal to bend the knee to Oda, or to execute enemies in accordance with the samurai code of honor, springs from a profound moral conviction—a belief in a future liberated from the excesses of martial violence. In one gorgeously observed sequence, the film pauses in its torrents of verbiage, while Murashige serves tea to one of his men. The silent respite might seem inconsequential, but, in its focussed display of tenderness and beauty, it feels more like a dramatic culmination, a declaration of principles, a glimpse of a world that’s genuinely worth fighting for. Throughout, “The Samurai and the Prisoner” is fascinated by the significance of the seemingly insignificant. It’s limited to a tense interlude, a blip in the history of a large-scale conflict. But a blip can contain multitudes, and this one allows Murashige to question every aspect of the social order that has shaped him. The answers, he suspects, may well hold the key to his nation’s future. ♦