Two-thirds of a masterpiece, Beasts of No Nation bristles with righteous judgment and fierce anger.

In adapting Uzodinma Iweala’s novel for the screen as a Netflix original film, writer/director Cary Joji Fukunaga wisely sets up the story in visual terms. Young Agu (Abraham Attah) lives with his family in an unnamed African country. Agu, his parents, his older brother, his younger sibling, and his grandfather live together in a small village. They must work hard, but they also enjoy the intimacy of their family relationship.

Agu loves to play — and strays into activity with his brother that borders on the criminal — yet he is also obedient to his parents. He is, in other words, a good boy, a typical kid who has been sheltered from the world by his circumstances. One day, that explodes. Rebel forces have risen up against the government, and their battle marches into Agu’s village, tearing apart his family and leaving him alone, racing into the jungle and fearing for his life.

There, he is forcibly recruited into the local branch of the rebel force, run by Commandant (Idris Elba), an ambitious, arrogant military man who rules by the sheer force of his personality and his ruthless disregard for the sanctity of life, whether friend or foe. Separated from his family for the first time in his life and scared senseless, Agu is nonetheless smart enough to recognize that the rebel force represents his only chance at survival.

Agu quickly adapts to the quasi-military regime and gradually becomes a trusted member of the brutal force, a standout in whom Commandant puts increasing confidence. Concurrently, though, Agu also gradually loses his humanity, his conscience wandering away as the rebel force becomes increasingly merciless.

Up to this point, Beasts of No Nation is a masterful, swirling portrait of innocence lost and inhumanity ingrained, a devastating tragedy that has a tremendous impact upon the psyche. Then the story turns, moving the relentless focus away from Agu, thereby weakening what has been built. The movie feels like it’s been trimmed down from something grander, something more far-reaching and elusive that the present version can’t quite reach.

Idris Elba is the foundation stone. His character is defined in ragged terms as a bully, a brute, a blast of evil; Elba ably personifies those qualities. He goes beyond that, suggesting hidden, disturbing nuances that eventually bubble to the surface, as well as the traits that limit his leadership potential. He may be an unquestioned threat locally, but that doesn’t mean he’s invincible.

Beasts of No Nation remains a staggering drama, a potent meditation on life and war and nationality and what’s really important to those who want to survive and make a difference.

The film opens on Friday, October 16 at Landmark Magnolia and on Netflix Streaming.