In the Garden of Beasts

lived in “a flat on Tiergartenstrasse,” he wrote, and she liked risk: “I knew her enthusiasm for danger and adventure.”
    His clues bring Martha immediately to mind, but she made no mention of such a journey in her memoir or in any of her other writings.
    Diels and his companion drove to Potsdam, then south to the border, where he left his car in a garage. He carried a false passport. They crossed the border into Czechoslovakia and proceeded to the spa city of Carlsbad, where they checked into a hotel. Diels also took along some of his more sensitive files, as insurance.
    “From his retreat in Bohemia,” wrote Hans Gisevius, the Gestapo memoirist, “he threatened embarrassing revelations, and asked a high price for keeping his mouth shut.”
    WITH DIELS GONE , many in Martha’s growing circle of friends doubtless breathed a little more easily, especially those who harboredsympathy for communists or mourned the lost freedoms of the Weimar past. Her social life continued to blossom.
    Of all her new friends, the one she found most compelling was Mildred Fish Harnack, whom she had first encountered on the train platform upon arriving in Berlin. Mildred spoke flawless German and by most accounts was a beauty, tall and slender, with long blond hair that she wore in a thick coil and large, serious blue eyes. She shunned all makeup. Later, after a certain secret of hers was revealed, a description of her would surface in Soviet intelligence files that sketched her as “very much the German Frau, an intensely Nordic type and very useful.”
    She stood out not just because of her looks, Martha saw, but also because of her manner. “She was slow to speak and express opinions,” Martha wrote; “she listened quietly, weighing and evaluating the words, thoughts and motivations in conversation.… Her words were thoughtful, sometimes ambiguous when it was necessary to feel people out.”
    This art of parsing the motives and attitudes of others had become especially important given how she and her husband, Arvid Harnack, had spent the preceding few years. The two had met in 1926 at the University of Wisconsin, where Mildred was an instructor. They married that August, moved to Germany, and eventually settled in Berlin. Along the way they demonstrated a talent for bringing people together. At each stop they formed a salon that convened at regular intervals for meals, conversation, lectures, even group readings of Shakespeare’s plays, all echoes of a famous group they had joined in Wisconsin, the Friday Niters, founded by John R. Commons, a professor and leading Progressive who one day would become known as the “spiritual father” of Social Security.
    In Berlin, in the winter of 1930–31, Arvid founded yet another group, this devoted to the study of Soviet Russia’s planned economy. As the Nazi Party gained sway, his field of interest became decidedly problematic, but he nonetheless arranged and led a tour of the Soviet Union for some two dozen German economists and engineers.While abroad he was recruited by Soviet intelligence to work secretly against the Nazis. He agreed.
    When Hitler came to power, Arvid felt compelled to disband his planned-economy group. The political climate had grown lethal. He and Mildred retreated to the countryside, where Mildred spent her time writing and Arvid took a job as a lawyer for the German airline Lufthansa. After the initial spasm of anticommunist terror subsided, the Harnacks returned to their apartment in Berlin. Surprisingly, given his background, Arvid got a job within the Ministry of Economics and began a rapid rise that prompted some of Mildred’s friends in America to decide that she andArvid had “gone Nazi.”
    Early on, Martha knew nothing of Arvid’s covert life. She loved visiting the couple’s apartment, which was bright and cozy and pasteled with comforting hues: “dove tans, soft blues, and greens.” Mildred filled large vases with lavender cosmos and placed them in front of a pale yellow wall. Martha and Mildred came to see each other as kindred spirits, both deeply interested in writing. By late September 1933 the two had arranged to write a column on books for an English-language newspaper called
Berlin Topics
. In a September 25, 1933, letter to Thornton Wilder, Martha described the newspaper as “lousy” but said she hoped it might serve as a catalyst “to build up a little colony in the English-speaking group here.… Get people together who like