The history of the Soviet gulag has been told before, most powerfully in Alexander Solzhenitsyn's epic, "The Gulag Archipelago," published in the 1970s. Yet so immense is this history, so vast was the whirlwind of terror that swept over the Soviet Union in the 1930s, that much is only now coming to light. The network of prison camps documented by Solzhenitsyn, we are learning, formed only part of the gulag system. There was a second or "hidden" gulag as well that destroyed the lives of millions of Soviet citizens.