Between 1976 and 1983, the military dictatorship in Argentina instituted state terror. According to the Mothers of the Plaza de Mayo, who bravely began demonstrating in the midst of the “dirty war”, 30,000 of their children were disappeared. Along with the Mothers came the Grandmothers of the Plaza de Mayo, whose specific aim was to locate the babies taken from so-called “subversive” mothers and given up for adoption, many to the military. Some babies were snatched from mothers by midwives just before the inevitable arrest and handed on to parents desperate for a child.

The narrator of Julián Fuks’s intense and hypnotic autofiction has an adopted brother who may have come into the family in this dramatic way. The stories their parents tell, despite the fact that both of them are psychoanalytic psychiatrists, never quite seem to satisfy the younger brother’s search for an answer to his brother’s origins as well as to his tangible difference. Like his older sister, the narrator was born once the parents – warned by a tortured colleague that arrest was imminent – had already escaped and settled in Brazil.

Exile, shifts in language and troubled pasts create the gaps in story that children always sense, but may not have the wherewithal to interrogate. When they do, they may well receive only those evasively protective, sometimes defensive tales about the bad times, or the days of political struggle. By the time children are old enough to understand, parents may already have consolidated memories of their own past that contain less than the whole picture.

Our narrator wants the whole truth – about his identity, his brother’s and his parents’ lives. It is hard to uncover, but he himself also resists discovery. He goes to Buenos Aires to try to dig truth out. Yet he can’t bring himself to knock on the door of his parents’ old address, or ring the number he knows is somewhere on a slip of paper and holds a clue to an adoption. Nor, though he joins their protest, can he make himself contact the Grandmothers of the Plaza de Mayo to tell them about his brother. He is both consumed by his own failures and somehow addicted to them. They are who he is.

The adopted brother has come to embody the whole family’s symptoms – the vessel that bears everyone’s difficulties

Resistance, in this tightly crafted and subtly translated work, is everywhere. It’s there in the parents’ initial resistance to military dictatorship. It’s equally present in their unwillingness, after a period in their new country, to dwell too much on the past. It’s there in the adopted brother’s inability to come to terms with the family he lives with and his recalcitrance when faced by analysts, including the parents. Above all, within the taut structure of this book, it’s there in the narrator’s obsession with his failure fully to embrace, to love, his brother; and indeed in every character’s reluctance to accept the truth of another, or of the history that might only be partially available in documents.

Mysterious holes in the past and the way they trouble successive generations are often present in the stories Holocaust children tell. Fuks evokes an Argentinian version, replete with similar patterns and hauntings. Halfway through the narrative, we realise that the adopted brother, despite everyone’s expressed care for him, has broken down – isolated himself in his room and come to resemble Kafka’s hunger artist, though the way the rest of the family treat him has echoes of Gregor in Metamorphosis. He’s been (self) relegated to insecthood, at once a scary and a crumbling alien:

I don’t even know how long it’s been happening, when talking about my brother became this vertigo, this daily act, this unavoidable fact of life. What could possibly still be left to say about his distance, his starvation, his resistance, his life lived out in solitude, a life interrupted by paralysis and silence … Where he goes when he does go out we don’t know, or with whom, what he does, where he loses himself. When he comes back, he shuts himself away in his room and leaves us advancing our flimsy theories, he’s enduring some distant suffering he does not recognise, he’s running away from his family because of undefined feelings of rage, because he’s crashing into some non-existent barrier, because he doesn’t want to face up to our difference. … Or maybe we are the ones who can’t bear his otherness …

Through a dramatic sequence of family therapy, change begins to happen. It becomes clear that the adopted brother has come to embody the whole family’s symptoms – the vessel that bears everyone’s difficulties. But how will the parents respond to their writer-son’s book about them all?

Fuks is superbly enabled in his autofiction by Daniel Hahn’s accomplished and sure-footed translation. Is there an irony in the fact that both writers are the children of Argentinian exiles and have parents enmeshed in the psychoanalytic profession? Whatever the case, this small book carries a big punch. It has already won prestigious prizes in Brazil, Portugal and Germany. Fuks is a young writer to watch.

• Lisa Appignanesi’s latest book is Everyday Madness: On Grief, Anger, Loss and Love (4th Estate). Resistance by Julián Fuks, translated by Daniel Hahn, is published by Charco. To order a copy for £11.43 (RRP £12.99) go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £15, online orders only. Phone orders min p&p of £1.99.