Excerpt from Agent Sonya by Ben Macintyre, plus links to reviews, author biography & more

This political radicalism was just a passing fad, Robert told Ursula. "In five years you'll laugh about the whole thing."

She shot back: "In five years I want to be a doubly good communist."

The Kuczynski family was rich, influential, contented, and, like every other Jewish household in Berlin, utterly unaware that within a few years their world would be swept away by war, revolution, and systematic genocide. In 1924, Berlin contained 160,000 Jews, roughly a third of Germany's Jewish population.

Robert René Kuczynski (a name hard to spell but easy to pronounce: ko-­chin-­ski) was Germany's most distinguished demographic statistician, a pioneer in using numerical data to frame social policies. His method for calculating population statistics—­the "Kuczynski rate"—­is still in use today. Robert's father, a successful banker and president of the Berlin Stock Exchange, bequeathed to his son a passion for books and the money to indulge it. A gentle, fussy scholar, the proud descendant of "six generations of intellectuals," Kuczynski owned the largest private library in Germany.

In 1903, Robert married Berta Gradenwitz, another product of the German Jewish commercial intelligentsia, the daughter of a property developer. Berta was an artist, clever and indolent. Ursula's earliest memories of her mother were composed of colors and textures: "Everything shimmering brown and gold. The velvet, her hair, her eyes." Berta was not a talented painter but no one had told her, and so she happily daubed away, devoted to her husband but delegating the tiresome day-­to-­day business of childcare to servants. Cosmopolitan and secular, the Kuczynskis considered themselves German first and Jewish a distant second. They often spoke English or French at home.

The Kuczynskis knew everyone who was anyone in Berlin's left-­wing intellectual circles: the Marxist leader Karl Liebknecht, the artists Käthe Kollwitz and Max Liebermann, and Walther Rathenau, the German industrialist and future foreign minister. Albert Einstein was one of Robert's closest friends. On any given evening, a cluster of artists, writers, scientists, politicians, and intellectuals, Jew and gentile alike, gathered around the Kuczynski dining table. Precisely where Robert stood in Germany's bewildering political kaleidoscope was both debatable and variable. His views ranged from left of center to far left, but Robert was slightly too elevated a figure, in his own mind, to be tied down by mere party labels. As Rathenau waspishly observed: "Kuczynski always forms a one-­man party and then situates himself on its left wing." For sixteen years he held the post of director of the Statistical Office in the borough of Berlin-­Schöneberg, a light burden that left plenty of time for producing academic papers, writing articles for left-­wing newspapers, and participating in socially progressive campaigns, notably to improve living conditions in Berlin's slums (which he may or may not have visited).

Ursula Maria was the second of Robert and Berta's six children. The first, born three years before her in 1904, was Jürgen, the only boy of the brood. Four sisters would follow Ursula: Brigitte (1910), Barbara (1913), Sabine (1919), and Renate (1923). Brigitte was Ursula's favorite sister, the closest to her in age and politics. There was never any doubt that the male child stood foremost in rank: Jürgen was precocious, clever, highly opinionated, spoiled rotten, and relentlessly patronizing to his younger sisters. He was Ursula's confidant and unstated rival. Describing him as "the best and cleverest person I know," she adored and resented Jürgen in equal measure.

In 1913, on the eve of the First World War, the Kuczynskis moved into a large villa on Schlachtensee lake in the exclusive Berlin suburb of Zehlendorf, on the edge of the Grunewald forest. The property, still standing today, was built on land bequeathed by Berta's father. Its spacious grounds swept down to the water, with an orchard, woodland, and a hen coop. An extension was added to accommodate Robert's library. The Kuczynskis employed a cook, a gardener, two more house servants, and, most important, a nanny.

Excerpted from Agent Sonya by Ben Macintyre. Copyright © 2020 by Ben Macintyre. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.