Sometime in 1953, when my mother was teaching at the American School in Mexico City, she did some private tutoring on the side. One of the kids she tutored was a boy named Bobby Stern, and we soon got to know his parents.

They were well known to the Hollywood-blacklist exile community we were part of: Alfred Stern was a famously left-wing financier, and his wife Martha Dodd Stern was a writer who had spent the 1930s in Berlin as the daughter of the then-U.S. ambassador, William Dodd.

I have few memories of the Sterns: a visit to their magnificent house set in walled gardens, and an evening when Alfred gave me a copy of Rabelais (I found it entertainingly gross). I vaguely remember Martha as a lively and funny woman, and Bobby as an odd, withdrawn boy.

But I well recall the news stories a couple of years later: We were returning to Mexico for a holiday, and the radio news reports were all about the U.S. government's efforts to get the Sterns extradited to face charges of spying for the USSR.

They managed to skip out of Mexico on Paraguayan passports, and we later learned that the Sterns had eventually settled in Prague. Martha had started a kind of finishing school for Soviet-bloc diplomats' wives, teaching them how to behave when their husbands were assigned to the West.

Later still, we learned that Alfred and then Martha had died in the East; rumor said Bobby, once diagnosed as schizophrenic, had returned to Mexico City.

Until I read Erik Larson's In the Garden of Beasts, however, I had had no idea of what a spectacular and horrifying life Martha Dodd Stern had lived in the early years of the Nazis.

William Dodd had not been President Roosevelt's first choice as ambassador to the new Hitler regime that had just taken power in 1933. In fact, he was the fifth or sixth choice, a Chicago history professor with ties to the old Woodrow Wilson Democrats. And Dodd himself would rather have stayed home to work on his history of the Old South, but the offer was a call to public service he couldn't turn down.

In the beast garden

Dodd also saw it as a chance to keep his adult children, Martha and Bill Junior, close to their parents for a few more years. So they sailed together for Germany along with the family Chevrolet. Soon they had settled into a rented house near the Tiergarten, the "Beast Garden" park by the Berlin Zoo.

Martha was 24 in 1933, an aspiring writer who had already had several affairs and a failed marriage to a young banker. Within a few weeks of her arrival in Berlin, she was sleeping with Rudolf Diels, the first director of the Gestapo, and expressing enthusiastic support for the Nazis.

Sure, they were giving the Jews a bad time, but no one liked the "chosen people" very much, including Ambassador Dodd and the affluent Anglo-Saxon diplomats in the U.S. State Department. Martha figured the Nazis would outgrow their anti-Semitism. Everyone else just hoped the Nazis would implode.

Her crush on the Nazis didn't keep Martha from also pursuing an affair with Boris Vinogradov, a Soviet "diplomat" who was of course an agent of the Communist secret police, the NKVD. And she may well have had an affair with Ernst "Putzi" Hanfstaengl, Harvard '09, who had taught Hitler how to use Ivy League cheerleading techniques to electrify political rallies.

Hanfstaengl also tried to soften Hitler's rough edges by fixing him up with Martha. Putzi arranged a "chance" lunchtime meeting, they shook hands, but no chemistry resulted.

Larson weaves several strands into his story, including William Dodd's doomed efforts to run a low-budget embassy; the prep-school grads back in Washington, who lived off private incomes, considered Dodd a hopeless hick. Moreover, he was criticizing the Nazis' policies when he should have stuck to nagging them about paying Germany's First World War indemnities.

Night of the long knives

As well, Larson follows the ugly incidents that erupted where Nazis and Americans met on the street. Several U.S. citizens were beaten by Storm Troopers for failing to salute the Brown Shirts' parades. Hitler promised to punish the guilty.

Instead, for internal political reasons, he punished the Brown Shirts altogether in the Night of the Long Knives. He arranged and directed the murders of the Storm Troopers' leader, Ernst Röhm, and hundreds of his followers. (Stalin, when he learned of this purge, expressed sincere admiration of Hitler's decisiveness, and emulated it a few years later when he launched his own Great Terror.)

This is the climax of the book, and a natural one. But the Dodds stayed on in Berlin for several more years, and I wish Larson had given those years the attention he gives to 1933-34.

His evocation of those years makes us wonder how Martha could have shrugged off the Nazis' behaviour, which amounted to state terror from the outset. Fellow travelers can always find excuses, but eventually Martha Dodd ran out of them.

Even her Gestapo lover had to disappear at times when he came out on the losing end of various internal party disputes. And many of Martha's German friends were losing their jobs or leaving the country. The Dodds' rented home was the bottom three floors of a mansion; the Jewish owner and his family lived on the fourth floor, charging the Americans a nominal rent and hoping their presence would deter the Nazis.

The ambassador as Cassandra

Ambassador Dodd tried to warn the State Department of the coming disaster, but his enemies dismissed him as an academic crank. Even the purge of the Brown Shirts didn't really concern the preppies in the State Department. They wanted Dodd to talk with the Nazis instead of standing up for American values.

Meanwhile, Dodd was trying to find a secure way to communicate when he was sure the embassy and his own home were bugged. Walks in the Tiergarten park were the only way he could safely talk with other diplomats.

On the rebound from the Nazis and infatuated by her Russian lover, Martha went on a tour of the Soviet Union. She came back disappointed with the Soviets but still in love with Boris. The NKVD considered her a potentially valuable agent, though they saw her as just a typical bohemian bourgeois American who would sleep with anyone attractive.

Eventually they did recruit her, though she seems not to have delivered any useful information. When the family returned to the U.S., Martha met and married Alfred Stern. (Boris died in one of Stalin's purges, his last love letter to her dictated by his executioners.) She helped publish a book about her father's experience in Germany, and a novel based on German aviator Ernst Udet.

With the end of the Second World War and the onset of the Cold War, prominent left-wingers found themselves suddenly as unpopular as Muslims would be after 9/11. The Sterns eventually left for Mexico, which for American Reds was something like the Netherlands for Anne Frank's family: Away from home, but not too far away.

But the Nazis invaded the Netherlands, and the American FBI and CIA operated freely in Mexico, grabbing people like Morton Sobell. They were close to grabbing the Sterns, and perhaps it would have been better for them if they had; their lives in Prague don't seem to have very happy.

Larson's book should make us reflect on the state of the world in the early years of the Depression, when anti-Semitic SS thugs in Hugo Boss-designed uniforms looked like a real solution.

And if those thugs weren't OK, then Stalin's thugs were the alternative. Otherwise you were stuck with the preppy anti-Semites in Washington, and their colleagues in Ottawa who thought "one is too many" was the right policy for Jews trying to escape Hitler.

We can't impose "presentism" on our grandparents. Capitalism had failed grotesquely in the Depression, and hadn't yet learned how to sell itself. The Nazis and Communists were self-taught masters of new media like film and radio, and knew how to offer their visions of racial or class Utopia.

Plenty of good people fell for one lie or the other. If you'd been alive then, and a believer in racial and gender equality, only the Communist Party would have welcomed you.

The great crime of the 20th century was the readiness to blame the world's troubles on some particular race, religion, class, or nationality. Erik Larson shows us both the criminals and their victims, caught in the act. And inevitably he reminds us of Santayana's warning: "Those who do not learn from history are doomed to relive it."