To fall into the clutches of the Soviet Union's penal system was infamously easy for Americans who went there from the 1930s to the 1950s. To get out was well-nigh impossible short of death, and little help was to be found from U.S. authorities.

Tim Tzouliadis, a documentary filmmaker born in Greece but educated and living in Britain, has written a book that can raise the ire and the hair of decent people everywhere. The outrages and horrors it recounts, buttressed by bristling documentation, overcome any shortcomings of its workmanlike writing style.

The author's entry to his story is the wave of Americans lured to the USSR during the Great Depression, either through desire for jobs in the so-called "workers' paradise" or through ideological commitment to communism, or both.

Some went on their own, some through the auspices of Amtorg, the Soviet trade agency. But the jobs and the hope quickly proved fleeting, and when they sought to return to their native land, they discovered there was no way out.

The Soviets routinely classified them as citizens, no matter what their passport status might be. They were labeled spies, traitors or other things -- it did not seem to matter to Stalin's minions. They did with their captives exactly what they or Stalin wanted.

The captured Americans were sucked down the rabbit hole of this dystopian Wonderland. Few got out alive. The great majority ended up in labor-camp prisons seemingly run by, not for, the criminally insane. Eventually they landed in the notorious Gulag where they were beaten, tortured, worked and starved to death, when not killed outright.

Nor did it end with the Depression emigrants. Tzouliadis refers to three generations of American prisoners. During World War II, American servicemen unlucky enough to fall into Soviet hands seldom got free. A similar fate befell Americans "caught" by various means in the late 1940s and early 1950s.

But it wasn't limited to Americans; among the millions in the Gulag were representatives of nearly every nation on Earth.

Fellow travelers such as singer-performer Paul Robeson and New York Times reporter Walter Duranty, who either chose not to see the cruelty or were taken in by the propaganda, are representative of the general indifference to the captives' fate.

But Tzouliadis' emphasis is on everyday Americans and their virtual abandonment by their government. Again and again he shows how diplomats in Moscow and bureaucrats in Washington declined to put forth much effort toward rescuing their countrymen.

The snatching of Americans slowed and ceased under Nikita Khrushchev. However, the captivity of those already ensnared did not end until the "Evil Empire" itself collapsed. A few managed to get out after decades of barbarous punishment.

Tzouliadis focuses particularly on two, Thomas Sgovio and Victor Herman, whose stories illustrate the courage and stamina -- and luck -- that was required to withstand such inhumanity.

The death toll of the Soviet system defies accurate measurement; the estimates of some respected scholars approach 20 million, most of the victims being Russians.

Revolutionary claptrap aside, the Soviets had simply ramped up the tsarist security apparatus built on secrecy, xenophobia and paranoia. And that attitude, as we see from observing the Russia of Vladimir Putin, has scarcely faded away.