The spy novel was the cold war genre par excellence, because the simplicity of geopolitics – two diametrically opposed powers, each jockeying for advantage – offered a perfect foil for the murkiness of the spy’s psychology. We are accustomed – after Graham Greene, John le Carre, and many others – to see the spy as the loose thread in the tight weave of ideology, where conventional moral certainties are frayed past recognition.

Marcel Beyer, the acclaimed young German writer, draws on these expectations in crafting his very unusual kind of spy novel. The title characters in “Spies” (Harcourt, 270 pages, $24) are not savvy agents but bewildered children, four cousins growing up in 1970s Germany. Their quarry is not secrets of state but family secrets, in particular the true story of the grandparents they have never met. The narrator and his three partners in discovery, Nora, Carl, and Paulina, are thus participating in their own small way in the national effort at Vergangenheitsbewaltigung – “overcoming the past” – that has dominated so much of German intellectual life in the last several decades.

In Mr. Beyer’s telling, this effort can no more arrive at a final reckoning with the past than the spy can uncover the real truth about his enemy’s government or his own. “Spies” does not allow its heroes, or its readers, the satisfaction of getting to the bottom of things. Instead, Mr. Beyer’s cloudy narration and dislocated prose aim to represent the permanent speculativeness that belongs equally to the spy and the child. For, as Mr. Beyer reminds us, we are all spies as children, trying to piece together the true and false stories that adults take for granted, or deliberately try to hide:

People steal glances at us, but no one looks us directly in the eyes anymore – neither foremen nor teachers nor salesgirls. As if they were afraid that in the presence of eyes like ours they might have to watch everything, and each one of us. As if we might steal something the moment their backs were turned. As if we might come after someone. As if we weren’t to be trusted.

Those “eyes like ours” are untrustworthy, not just because they are constantly peering, but because of their disturbing color: the narrator and his cousins have “Italian eyes,” darker than the blue eyes all around them. This freighted difference is, in fact, the first clue to the mystery that absorbs the children, during the shared summer vacation that is the novel’s focus.

According to family lore, the children inherited these eyes from their grandmother, an opera singer who died before they were born. They have never been able to get the true story, however, because they have been forbidden all their lives to meet their grandfather, though he lives just a few streets away with his second wife. That wife, known only as “the Old Lady,” is supposedly to blame for the interdict: The children have heard stories about her instability, her cruelty, her unremitting hostility to every reminder of her husband’s past.

As this brief summary shows, many elements of “Spies” are obviously allegorical; the local circumstances of the children’s lives encode a generation’s experience. Just as the children’s eye color symbolizes their dissent from the Aryan norm, so their neighborhood – built literally on top of a garbage dump – makes literal their sense that something is rotten in the Federal Republic. When it turns out a giant mushroom is growing underneath the town and befouling the air with its spores, Mr. Beyer’s symbolism goes beyond crudeness to a kind of magic realism: “To tell the truth,” the narrator says, “I don’t much like the smell that comes across the fields with the spores. In fact, I wish the smell that arrives with the setting sun would disappear, it’s so sweet and thick you feel as if you can barely breathe.”

If Mr. Beyer’s symbolism is not subtle, his handling of narrative is adroit, and he continually blurs the boundaries between what the children think they know and what they imagine or invent. As one scene abruptly gives way to the next, it takes the reader a moment to orient himself: Are we reading about the grandparents or the grandchildren, the past or the present? And as the novel follows the young spies into their own adulthood, even the few truths the reader took for granted come into question.

Is their grandmother dead at all, or could she be, as the narrator imagines in one deliberately unlikely scenario, still alive and singing in Italy? Is the Old Lady really the madwoman she has been made out to be all along? Mr. Beyer offers only subtle and hesitant clues to the truth, forcing the reader to become a kind of spy himself, and allowing certain revelations to strike with overwhelming force.

There is an element in “Spies,” however, that remains troubling in a way other than Mr. Beyer seems to intend. In the novel’s allegorical scheme, it is clear that the narrator’s grandfather – who, we learn early on, was part of the Luftwaffe’s Condor Legion, responsible for the destruction of Guernica, among other atrocities – represents the nation’s shameful Nazi past. The dead grandmother, a cultured artist who turned a blind eye to her husband’s secret missions, is fairly legible as the lost Germany of Dichter und Denker, itself subtly implicated in German crimes.

Mr. Beyer’s greatest animus, however, seems to be reserved for the Old Lady, who can only be read as an emblem of the postwar Federal Republic, neurotically obsessed with hiding every trace of the nation’s past. It makes sense that Mr. Beyer, born in 1965, would feel more personally outraged by this regime of secrecy, which he experienced, than by the Nazi regime, which he did not. Still, the narrator’s loving nostalgia for his grandparents, who are guilty of Germany’s great crimes, sits oddly with his hatred for the Old Lady, who is in any objective reckoning far less culpable.

Perhaps this longing for the past, even the guilty past, is one of the subtlest stigmata of Germany’s postwar generation, doomed, as Mr. Beyer effectively shows, to an eternity of spying: “The moment Nora, Carl, Paulina and I were born,” the narrator realizes near the end of the book, “we were immediately included under the ban on memories, were drawn into the tormented aversion to anything connected with our grandmother, in spite of the fact that she had died long before we came into the world. We have no memory of her: even with the best will in the world, we wouldn’t be able to remember a thing.”