About midway through the darkly engrossing novel “A Million Drops,” a young woman with too many questions on her mind arrives at the hellscape of a desolate Western Siberian town.

Black clouds of insects hover over the swampy beach. Nothing else, not even river grasses, can find purchase there.

“A Million Drops,” by Victor del Árbol (Other Press)

Tania, one of many tormented and searching souls in the Spanish author Víctor del Árbol’s sprawling work, turns to the ferry­man and asks what happened in this place, a town with a notorious legacy called Nazino. The man shrugs.

“Things from the past,” he says.

Unanswered questions and vague retorts run throughout “A Million Drops,” a book that traces the murky saga of the Soviet Union’s engagement in the Spanish Civil War, a conflict that many modern-day Spaniards still struggle to process. The book, originally published in Spain in 2014 and now available in the United States in a crisp English translation, has added to the acclaim of del Árbol, a former Catalan police official and erstwhile seminarian.

Del Árbol routinely accumulates European crime-writing prizes, but “A Million Drops” is an effort that defies categorization, pulling together the best elements of historical fiction, psychological thrillers and literary character studies. The book begins with the murder of a young child in the early 2000s. But the killing at a lake outside Barcelona is only a launching-off point for del Árbol to unspool a dizzying multigenerational drama that begins in the years before the 1930s Spanish Civil War.

The central figures in the book are Gonzalo Gil, a discontented Barcelona lawyer, and his father, Elías Gil, an anti-fascist folk hero renowned for his efforts to save refugees fleeing the victorious forces of the future Spanish dictator, Gen. Francisco Franco. Franco’s troops were backed by Hitler and Mussolini, while the losing Republican forces of the democratic Spanish government were supported by a complex and often feuding coalition that included anarchists, communists and Stalin’s Soviet Union.

As a young man before the war, the elder Gil travels to the Soviet Union to work on grand public-works projects, along with others from throughout Europe entranced by the promise of a new political paradigm. He is falsely labeled as anti-Bolshevik and is sent to Nazino Island, where thousands of deportees died while stranded in miserable conditions that remained mostly secret until a historical reckoning many decades later. Gil survives Nazino, only to return to his native Spain, a country soon decimated by war.

The narrative meanders into the grim recesses of a child prostitution ring in Spain run by sinister Russian mobsters with ties to some of the more menacing characters Elías Gil encountered during his Soviet misadventure. The monstrous trafficking organization is known as the “Matryoshka,” a name given to the famed Russian nesting dolls.

Gil’s son is left to try to untangle how the madness intertwines with the tortured history of his mythic and mysteriously vanished father. He undertakes the quest after the suspicious death of his sister, Laura, a journalist turned police officer whose life is wrecked by her obsessive investigation of the sex ring. Before her death, Laura is so consumed by what she learns that her husband begs her to give up, saying “she couldn’t fight all the evil in the world by herself, that her efforts were a drop in the ocean.”

The author Victor del Árbol (Victor del Árbol)

The title of the book derives from her response: “What is the ocean, if not a million drops.”

Del Árbol embroiders his book with characters that might seem to be drawn straight from the noir playbook. There is a sassy secretary, an unfaithful wife, a wealthy and heartless father-in-law and a corrupt cop with “sweat stains at his armpits,” a belly that “threatened to pop the buttons off his waistband”and a habit of smoking Ducados, a ferociously strong Spanish cigarette. As the story unfolds the bodies begin to pile up.

But what elevates the book, which for all its merits would have benefited from a bit of trimming, is del Árbol’s nuanced sketches of these stock characters. The author is clearly intrigued by the very nature of man’s propensity toward violence. Even the villainous Igor Stern, a brutal shape-shifter who is Elías Gil’s decades-long rival, isn’t above pondering why he does what he does.

“I’ve read a few books and met a few people over the years,” Stern tells Gil. “And they’ve all taught me that there exists a sublime pleasure in the elegance of our violence when we express our feelings. An aria, when it comes down to it, is not so different from a battle cry.”

The battle that Gil cannot leave behind is the war that rived his nation. He recalls traveling to Leningrad during World War II and finding fields of dying Spanish volunteers who joined the Nazi forces in the infamous siege of that city.

“Why are you here, fighting a war that isn’t yours?” he asked one soldier.

Gil points a gun barrel to the man’s forehead, but before he can pull the trigger, the soldier yells out: “Arriba España, you Red bastard!”

That night, Gil writes home to his wife.

“How much damage did the war do to Spain?” he asks. “Too much. I wonder if we’ll ever manage to leave it behind, and I’m terrified of the answer.”

Manuel Roig-Franzia is a writer in The Washington Post’s Style section.

A MILLION DROPS

By Víctor del Árbol. Translated from the Spanish by Lisa Dillman

Other Press. 629 pp. Paperback, $19.95