Early on in the movie adaptation of Uzodinma Iweala’s 2005 novel, Beasts of No Nation, Agu, the preteen protagonist, and his unnamed older brother have just pulled off an impish scam — demanding money from a passing driver to remove a tree branch they themselves had hacked down to block the road — when they are accosted by a wild-haired old lady. Agu’s father, a local schoolteacher, has set aside some of his family’s land to shelter refugees displaced by the escalating civil war in this unnamed West African country — land the furious “witch woman” maintains is hers. “I know your whole family!” she raves. “The devil will bless you one by one!” Later, when troops from the ruling National Reformation Council arrive and line up nonpartisan townsfolk, including Agu and his family, the old woman makes good on her curse by claiming not to recognize them. “They are not from here,” she tells the soldiers. “They must be rebels.” Agu escapes, but his father and brother are summarily executed as spies.

The tidiness of this narrative arrangement is typical of the film, and instructive as to the distortions inherent in the adaptation process. In Iweala’s novel, his father’s execution happens not because he is betrayed by an incidental character but because senseless, indiscriminate killing is the air the novel breathes. It’s debatable, of course, whether the restless momentum of film demands the strict causative logic of A-leads-to-B, or whether this is merely an orthodoxy that has hardened into a rule, but in Beasts of No Nation the adherence to the creed of character motivation (by Cary Joji Fukunaga, directing his own adapted screenplay) has damaging consequences for the film’s persuasive power. Toward the end of the film (readers may take this spoiler alert as due notice of all the spoilers to follow), after Agu has been pressed into child soldiery, the leader of the rebel unit, who is known only as Commandant and is played by Idris Elba, is abandoned by his battalion when a rift with the Supreme Commander — Jude Akuwudike, Bond-villainous in his crisp diction and white short-sleeved safari suit — results in a desperate shortage of supplies. In the book, one of Agu’s fellow insurgents simply gets fed up one day and guns Commandant down. “Commandant is dead,” observes book-Agu, flatly. “It was so easy to be killing him.”

Still from Beasts of No Nation. Courtesy Netflix

Where the movie, then, is conventionally dramatic, the novel derives its affect precisely, and paradoxically, from the affectlessness of Agu’s narration and the breakdown of meaningful causation it both enacts and describes. The universe of the movie is still moral; actions have consequences. In the novel, as Agu gets high on “gun juice,” a presumably amphetaminic stimulant “tasting like bullet and sugarcane,” and learns to kill without compunction, past and future give way to a perpetual depthless present of numbed barbarity. We are moved because Agu isn’t. The novel’s argot, whose rhythms and syntax are reportedly imitative of several Nigerian languages, underwrites this sense of blank, ceaseless futility by subsuming events into a pidgin present continuous. “All the time bullet is just eating everything, leaf, tree, ground, person — eating them — just making person to bleed everywhere.” “I am wanting to kill; I don’t know why. I am just wanting to kill.”

The idiom is preserved in the adaptation, both in dialogue and in Agu’s voice-over, but to less purpose. The language resists affect while the movie perseveres in imposing it. One unexpected corollary of Fukunaga’s insistence on cause and effect, on an audit trail of explicability, is his squeamishness with regard to atrocity. From one perspective, this is defensible, since film is a literalist medium whose depictions of extreme violence can’t avoid being more explicit than they appear on the page. When a small girl is torn from her mother and stomped to death, or Agu is sexually abused by Commandant, it’s both ethically and aesthetically justified that the camera, no less than the audience, should want to look away. But in another respect, the movie’s representations of violence are unduly cautious. In the book, when Agu and his mute friend, Strika, discover the mother and child hiding under a bed, the wrenching horror of what follows derives not only from the acts described but from Agu’s dissociated description of them: “I am standing outside myself and I am watching it all happening.” On-screen, by contrast, Agu cuts short the mother’s rape by shooting her in the head — horrific, for sure, but also an act of mercy. Here, too, the urge to explanation and motivation places Agu’s actions in a coherent moral context, and thereby squanders the opportunity to show these horrors for what they are, however much we might sympathize with Agu’s own brutalization: irredeemable.

Agu’s first kill is another case in point. In Sin Nombre (2009), Fukunaga’s feature-film debut, a boy of roughly Agu’s age is initiated into the Mexican branch of the Mara Salvatrucha after being coerced into shooting a member of a rival gang. Almost exactly the same thing happens in Beasts of No Nation, in which Fukunaga decorously cuts away from the gruesome image of an enemy soldier’s skull being split first by Agu’s machete, then by Strika’s, to a muffled slow-motion shot from somewhere near the dead man’s (impossible) point of view, as the boys hack him to pieces and the camera lens is spattered with blood. At the start of the movie, before war has reached the village, Agu and his friends are seen trying to peddle the eviscerated cabinet of an old TV set to the Nigerian peacekeepers who patrol the buffer zone. “It is imagination TV,” goes Agu’s sales pitch, as his best pal pokes his head through the frame to demonstrate its 3-D capabilities. It’s a charming sequence, feistily played by the kids, and eloquent — if a little unsubtly so — about the unreality of war to children (and moviegoers) whose experience of it is (so far) limited to mediated images. In the machete scene, the blood-spattered lens recalls that earlier, more innocent state, and conforms to the derealization that Agu experiences in the corresponding passage in the book:

Strika is joining me and we are just beating [the enemy] and cutting him while everybody is laughing. It is like the world is moving so slowly and I am seeing each drop of blood and each drop of sweat flying here and there.

Except that in the movie it’s the viewer, not Agu, who is estranged from the reality of the soldier’s murder. The spatters of blood draw more attention to the lens than they do to themselves. Time and again the medium militates against our immersion in it.

The result is a film that is at once diligently dramatic and oddly becalmed, a film about unutterable horror that isn’t particularly horrifying. As Commandant, Elba is slow-moving, bearish, a pinch or two less trim than he was as Stringer Bell, given to rousing speeches and the languid hand gestures of a hip-hop M.C. in wearyingly humid conditions. If his swagger has an actorly, self-regarding quality — a slow roll to his gait, a delectation in each long pull on his cigarette — that is apt enough in a character whose authority is grounded in little more than self-assertion. Kept waiting for hours, then effectively demoted by the rebels’ Supreme Commander, Commandant abruptly becomes yesterday’s man, and in his mortification Elba brilliantly succeeds at exposing, if only for a moment, the frightened little boy inside a man who has denied so many their childhood. Still, I wonder if Elba doesn’t bring something a little too conventionally charismatic to the role, particularly by comparison with Abraham Attah’s Agu. As happens so often with child actors, Attah, a fifteen-year-old Ghanaian with no movie experience, doesn’t so much act the part as disregard the distinction between acting and being himself. His transformation matches Agu’s, as both boys, real and fictional, become the child soldier with equal unself-consciousness: speechless with fear in his first interrogation by Commandant, grimly comic marching through the bush in his outsized helmet, a child again playing blindman’s buff with Strika during a rare and joyous respite from active deployment. It’s in Attah that the movie comes closest to the novel’s disquieting, engrossing directness.

Fukunaga’s last film was an accomplished, subdued adaptation of Jane Eyre (2011). Whereas in that film, working off Moira Buffini’s quietly ingenious screenplay, Fukunaga was content to point the camera and let it follow the cerebral cut and thrust of his protagonists’ courtship, Beasts of No Nation betrays the weakness for portent so amply demonstrated by the first season of True Detective (HBO), which Fukunaga directed. Notwithstanding Woody Harrelson’s appeal, the show suffered from a thin plot padded out with the insufferably pretentious hogwash spouted by the Matthew McConaughey character, and resolved on a perp whose sickening voodoo-flavored degeneracy seemed, on the basis of his lair, to go hand in hand with haute couture set-design skills. Nothing so preposterous afflicts Beasts, but there are traces of this dramatic overdeterminism in the percussive cuts to black when Agu is captured by the rebels, and in what we might call Fukunaga’s trademark oh-my-God-now-we-realize-the-extent-of-this crane shot, as Dan Romer’s score throbs discordantly and the camera rises diplodocuslike to take in the rebel encampment.

Again, it’s tempting to lay this tendency to overemphasis at the adaptation’s door. To discard the novel’s flashback structure in favor of simple linearity is to expose Agu’s story, for all its incident, as a succession of inevitabilities, impassively told. One might therefore conceive of Fukunaga’s interventions as understandable efforts to compensate for a basic dramatic deficit in Iweala’s story. But the effect is no less distancing than his urge to contextualize its atrocities, and the reminders of the movie’s artifice come at the expense of its ability to move us. In the novel, Agu recalls a village initiation ceremony in which an ox is killed and the local boys, wearing leopard and ox masks, rub its blood on their bodies. Then the masks are removed and “all the boy is becoming men.” Unable as the movie is to recount Agu’s prehistory, it transfers initiatory responsibilities to the rebel battalion; in one sequence that comes complete with herbal benedictions, spaced-out chanting, and cod-occult skull-arches in the True Detective vein, Agu and his fellow recruits are ceremonially “executed” by firing squad in order to be reborn as soldiers. All very well, but if it’s authentic, I’m a witch doctor. What’s more, Agu’s hazing by the rebels in the movie literalizes a process that Iweala leaves to unfold by implication — Agu’s coming of age. As ever, Fukunaga yields to the impulse to intrude and editorialize.

The same might be said of the film’s cinematography, which goes crazy-colored when the drugs kick in and the rebels mount a frenzied attack on an enemy stronghold. Many of these images are striking, even beautiful, but it’s hard not to feel that they emerge more from the desire for a pretty shot than from the truth of the material. In any case, they pale in comparison to the martian poetry of book-Agu’s fresh view of the world:

We are at the camp and I am watching how the sun is just dropping down behind the hill like it is not wanting to be seeing us anymore. All the color is leaking out of it and looking like flame from hell all over, eating up the top of all the tree, making all the leaf bright, bright. Suddenly it is night.