Ten years ago, on a blustery March morning, I found myself in front of Moscow’s infamous Lubyanka prison, the dreaded home of the KGB, where thousands of political prisoners were jailed, interrogated, and tortured. I had come to find the file of my father, a man I did not know — a man who, when he was arrested in the hellish days of Joseph Stalin’s purges, was not even half the age I am now.

The dark central stairwell in the Lubyanka annex where I was directed was barely illuminated; a sole light bulb hung above the second-floor landing that housed the reading room. There, I was handed his file under the watchful eyes of a couple of dour officials behind an all-glass wall. My Russian guide, Lada, nervously translated the contents, while I stared at my father’s mug shot taken at the Butyrskaya Prison, built in the time of Catherine the Great and still the largest in Moscow. He looked haggard and soulful.

The file revealed that my father, Wilhelm Schwarzfeller, a German national, had been an agent for Red Army intelligence in the 1930s before being arrested in Moscow in January 1938 during Stalin’s Great Terror. I was just a baby, born only six months before in Los Angeles, and too young to have any memory of him. He had been sentenced to an eight-year term in Vorkuta, one of Stalin’s Gulag prisons north of the Arctic Circle, where he starved to death in 1943. My mother and I left Moscow during the German invasion and returned to America, where I grew up without a father. My mother, born in Ukraine but a naturalized U.S. citizen, deflected or simply ignored my questions about him — and for good reason.

As a boy in the late 1940s and 1950s, I was imbued with America’s collective anxiety about the “Red Menace” that so occupied the waking hours of FBI Director J. Edgar Hoover and Sen. Joseph McCarthy. Legions of Soviet spies, it was thought, lurked everywhere. But it came as a shock when I learned from the Lubyanka file what I had long suspected — that my father was one of those spies.

Soon thereafter, and with a sigh of great relief, I learned that he never spied against the United States. Instead, his principal mission was to spy for the Soviets against Japanese-occupied Manchuria. Stalin was greatly concerned about the intentions of the increasingly militaristic Japan toward the Soviet Union. Would Manchuria, abutting its Siberian border, become the launching point for a Japanese invasion? After all, Japan had thrashed the tsar’s military in 1905, becoming the first Asian country to best any of the Western powers. My father, I learned, had been stationed in Mukden (now Shenyang), posing as a Canadian businessman.

I knew none of this, however, until that morning in the Lubyanka; I had spent most of my life thinking of my father as a distant figure, a ghost. Since then, though, I’ve found that I was not alone in finally deciding to unwind my family’s hushed secrets, in my refusal to keep them buried in a sort of personal Cold War vault. I’ve spent the last few years working to re-create and write of my father’s journey and secret life — and while doing so, I’ve encountered many other spy kids along the way who also decided to investigate the mysteries of their missing dads.

The children-of-spies memoir, it turns out, is a virtual cottage industry these days. Consider just this recent sampling: John Richardson’s My Father the Spy: An Investigative Memoir (2005), Lucinda Franks’ My Father’s Secret War: A Memoir (2007), Jimmy Burns’ Papa Spy: Love, Faith, and Betrayal in Wartime Spain (2009), Sara Mansfield Taber’s Born Under an Assumed Name: The Memoir of a Cold War Spy’s Daughter (2012), Scott Johnson’s The Wolf and the Watchman: A CIA Childhood (2012), and Carl Colby’s soon-to-be-released The Man Nobody Knew: In Search of My Father, CIA Spymaster William Colby.