Amy Adams plays a linguist tasked with translating messages from alien visitors—and determining what they seek. Illustration by Keith Negley

When aliens come, how will they get here? Well, unless they are sly infiltrators of the flesh, they will probably go for the kind of boastful, get-a-load-of-us craft that was immortalized by Douglas Adams in “The Hitchhiker’s Guide to the Galaxy.” He wrote, “The ships hung in the sky in much the same way that bricks don’t.” That was true of “Independence Day,” and it is doubly true of “Arrival,” in which a dozen mountainous ovoids—charcoal gray and rough to the touch, like a pumice stone—show up at various locations around Earth. Rather than land, the vessels suspend themselves in dignified fashion, with their tips facing downward and not quite touching the ground. Whatever their occupants want, it’s a pretty cool way to make an entrance.

But what do they want? No ultimatum is issued; no humans are abducted and probed until they blush; no hairless mini-travellers trot out to say hello. In the face of this stonewalling, Dr. Louise Banks (Amy Adams) is summoned to the cause. She is, you will be heartened to hear, a linguist by trade. Add her to the botanist played by Matt Damon, in last year’s “The Martian,” and you sense a new Hollywood trend, whereby superheroes and special agents will be gradually replaced by people with proper jobs. The question is not who will play James Bond but whether Bond should retrain as a geography teacher. Jack Reacher could be huge in plastics.

The director of “Arrival” is Denis Villeneuve, who is both a brooder and a tease. Anyone who saw “Prisoners” (2013), “Enemy” (2014), or “Sicario” (2015) will know how sparing he can be with facts, divulging them slowly as the tale gets under way. You have a clue what’s going on, but no more than a clue, and what you learn is far from comforting. So it is with Louise, who finds herself lecturing, at college, to an almost empty room. Cell phones are ringing. Outside, as she walks to her car, fighter jets hurtle overhead, like thunderclaps. At home, where she lives alone, she goes to bed with the television on and the news channels in a frenzy. The next day, she is approached by Colonel Weber (Forest Whitaker), from Army Intelligence, who plays her a recording of unearthly noises—knocks and clicks, with a hint of moan—and asks if she can translate. Louise is perfectly clear on the matter; she can’t hope to understand such a vocabulary, if that’s what it is, unless she meets the speaker face to face. Or, as things turn out, face to sucker.

The first forty minutes of “Arrival” consumed me utterly. I gave up taking notes and resorted to scrawling sketches in the dark, as one prodigious image followed another. So sure is the stride of the narrative, and so bracing the air of expectation, that you feel yourself, like Louise, beginning to spin, and barely able to catch your breath. She is borne away, by night, in a military helicopter, introduced on board to Ian Donnelly (Jeremy Renner), a scientist from Los Alamos, and flown to Montana, where one of the spaceships has come to rest. Until now, we have been granted mere glimpses of them, as granular smudges on a TV screen, but now we are blessed with a prime example, on a beautiful day. Behold the great mass of the thing, standing prouder than a neolithic stone, with green prairies beneath and billows of bright fog streaming off the hills and breaking around it like waves. David Lean would have approved.

The test, of course, is what happens when you enter the craft. The Special Edition of “Close Encounters of the Third Kind” tacked on a scene of Richard Dreyfuss goggling inside the mother ship, to no avail. All we needed was to see him walk up the ramp, and what he found within—basically, a mall designed by Busby Berkeley—was so much less witty than the fairground-like exteriors that it bled the movie of imaginative power. “Arrival” does things differently. For a start, within the belly of the vessel, gravity takes a holiday. At one point, Louise and Ian—small figures in protective orange outfits, shepherded by Weber and other personnel—are seen advancing cautiously, upside down, along the ceiling of a vast gray vault. If they practiced long enough, and ditched the suits for white waistcoats, maybe they could dance there, like Fred Astaire in “Royal Wedding.” Hence the grin that Ian can’t suppress. The physics he thought he knew just flew away.

As for the aliens, suffice to say that nothing you’ve ever eaten, even in a Greek restaurant, will prepare you for tentacles like these. Shaking hands is not recommended, unless you’ve got a spare afternoon. The newcomers are set apart, at the far end of the vault, by a transparent wall, behind which they drift in a hazy medium. Their gestures are nicely poised between a writhe and a waltz, and, for particular emphasis, they like to hit the wall with a scary splat. To Louise’s infinite satisfaction, when she shows them a word—her species, or her name—on a whiteboard, they write back, not in script but in mottled black circles that they describe in elegant squirts, daring her to decipher every blot. All this puts the visitors in good company. Aristotle, another ancient philosopher complained, “surrounds the difficulty of his subject with the obscurity of his language, and thus avoids refutation—producing darkness, like a squid, in order to make himself hard to capture.” Louise speaks Mandarin, among other tongues, but those are no help. How do you become fluent in monsters’ ink?

For better or worse, it’s a question that Villeneuve and his screenwriter, Eric Heisserer, prefer to duck. Halfway through the film, as Louise is preparing to solve the circular codes, we get a lumpy voice-over, explaining that she has cracked them and updating us on her progress. Suddenly, she is scrolling through extraterrestrial symbols on her tablet and matching them to English nouns and verbs. Huh? Did the studio take fright at the prospect of linguistics? Was the Pentagon concerned that hackers might communicate in squid? There are splendid things to come, in “Arrival,” but somehow, from here on, the focus is blurred. We get a rushed and scruffy subplot about a plan to sabotage the craft, and an expansion of the movie’s range—reports from China, Russia, and other interested parties, declarations of war against the aliens (on the strength of one translated word), and Louise single-handedly striving to halt the meltdown. The moral of the tale is that our world could be as one, if only we could all talk the same talk. You know, like Esperanto. That worked out well.

None of which, I hasten to add, is a reason to skip “Arrival.” It may be weaker in the resolution than in the setup, but that is an inbuilt hazard of science fiction, and what lingers, days after you leave the cinema, is neither the wizardry nor the climax but the zephyr of emotional intensity that blows through the film. The dominant feeling, strange to say, is sadness, which may cause audiences who associate spaceships with the zap of merry mayhem to stir uneasily in their seats. The first thing we get in the movie, even before the aliens roll up, is a flashback—or, at any rate, a flash—to a daughter whom Louise bears, raises, loves, and loses to illness. The ensuing grief refuses to dispel. Indeed, it may account for the hunger with which she greets the news of visitors from beyond as though it were an annunciation: a shaft of light to pierce her private gloom. What happens to that hope, and how Villeneuve plays around with time in order to extract the maximum fervor from Louise’s experience, I won’t reveal, not least because I’m too dumbfounded—or simply too dumb—to have worked it out yet. The most accurate guide to such mysteries is Jóhann Jóhannsson’s music, which is rife with choral chanting, swelling brass, skitterings, and booms. Is it based on the heartbeat of the beasts? Should we be threatened or thrilled?