One hallmark of a gifted novelist is the ability to see the potential for compelling fiction in an incident, anecdote or scrap of history, no matter how dry or seemingly obscure, that others have overlooked. By that standard and several others, the career of Juan Gabriel Vásquez, a Colombian writer born in 1973, is off to a notable start with “The Informers,” his ambitious first novel.

Juan Gabriel Vasquez

His subject is one of the least-known episodes of World War II. Fearful of Nazi influence in Latin America, the United States, acting through J. Edgar Hoover’s F.B.I. and the State Department, compiled a list of suspected Axis sympathizers and then pressured compliant governments to intern those named, often on the basis of sketchy or dubious intelligence.

Anti-Fascist refugees from Germany and Italy, along with the descendants of immigrants from those countries and Japan, were snared in that net and frequently imprisoned together with real Nazis. There were other abuses: corrupt government officials and covetous neighbors would sometimes falsely accuse prosperous émigrés, hoping to gain control of their expropriated businesses and homes.

“The system of blacklists gave power to the weak, and the weak are the majority,” one character in “The Informer” muses bitterly. “That was life during those years: a dictatorship of weakness. The dictatorship of resentment,” in which there were thousands “who accused, who denounced, who informed.”

Nearly 7,000 Axis nationals even ended up in internment camps in the United States, held in escrow for bargaining purposes and in some cases detained well after the end of the war. Mr. Vásquez, however, focuses on a much smaller group and topic: German immigrants to Colombia and the corrosive effect their plight had on their native-born children.

The parallels with the contemporary war on terror are clear, though Mr. Vásquez chooses not to make them explicit. In remarks last year to the PEN American Center, he recalled Balzac’s maxim that “novels are the private histories of nations,” and that is the approach he deftly applies here, telling his story through the experience of three families. At the start of “The Informers,” a young Bogotá writer named Gabriel Santoro has just written a book about the Enemy Alien Control Program, as Washington called it, based on the recollections of Sara Guterman, an elderly German Jewish émigré and family friend. To his shock and distress his father, a distinguished professor of law and oratory also named Gabriel, savages the book in a review, causing a rift between the two.

The younger Santoro eventually discovers the reason for this extreme reaction: his father’s fear that his own treachery during the period will be exposed. As the son digs deeper and learns more about what really happened back then — with the help of Sara, who becomes his informer — his father’s belated efforts at expiation and reconciliation also come to light.

Running like an undercurrent through “The Informers” is the violence that has pervaded Colombian life for decades, leaving survivors with the “fleeting altruistic regret one tends to feel when listening to news of someone else’s death.” A cavalcade of assassinations, kidnappings, bombings and other terrorist attacks perpetrated by guerrillas and drug lords are mentioned in passing, so casually that when one character is asked about the death of a lover, she replies: “There was a fight and guns came out and he got shot, nothing more. The most normal thing in the world.”

Mr. Vásquez also proves adept at capturing the sense of dislocation and vertigo experienced by those forced to separate from their language and culture. Novels about immigrants have become a genre of their own in recent years, usually centered on Latin Americans or Asians trying to make their way in the United States or some other industrialized country. Here, though, the positions are reversed, and while one Nazi supporter sneers at Germans in Colombia who “wanted to assimilate” and have “done so downward,” Mr. Vásquez clearly sympathizes with those struggling to adjust.

“He had been forbidden spontaneity,” laments the Colombian wife of a German immigrant, “the capacity to react unthinkingly, to make a joke or ironic remark, all the things that people who live in their own language can do. ...What he said was too meditated or stilted to forge a friendship with anybody.”

Like all Colombian writers of his generation (and no doubt those to come) Mr. Vásquez must labor in the shadow of the Nobel laureate Gabriel García Márquez, exponent of the literary style known as magical realism. He playfully seems to acknowledge that burden when his narrator, after reading Mr. García Márquez’s first novel, “Leaf Storm,” in school, enters a literary contest and is accused of “cheating and dishonesty for having entered a story in the competition that an adult had written.”

In sharp contrast to Mr. García Márquez’s levitating priests and very old men with enormous wings, “The Informers” is a straight-ahead, old-fashioned narrative, though not necessarily linear. Mr. Vásquez moves back and forth between the 1980s and ’90s and the 1930s and ’40s, but shows restraint, addressing history rather than myth. He avoids unnecessary pyrotechnics, perhaps out of respect for the gravity of his subject.

If anything, he would seem to owe a debt to Joseph Conrad, of whom he has recently written a biography, and Borges. The twin themes of betrayal and atonement in “The Informers” recall Conrad, specifically “Under Western Eyes.” And Mr. Vásquez’s second novel, “The Secret History of Costaguana,” not yet available in English, offers a Borges-like alternate version of Conrad’s “Nostromo” in which Conrad himself is a character.

Two years ago Mr. Vásquez was included on a list of the most “important” Latin American writers under 40, nominated by more than 2,000 authors, literary agents, librarians, editors and critics. “The Informers” alone justifies their choice, given its challenging subject and psychological depth, but clearly there are bigger and even more intriguing things on the way.