There are plenty of must-read books on Stalinism and the Gulags, many of which are far better known than this, but 'Into the Whirlwind' is possibly the most powerful I have read. It's the autobiography of a woman caught up in Stalin's terror of the 1930s onwards, and every page seems very immediate and personal.
Engrossing, horrifying, and above all deeply humanistic, 'Into the Whirlwind' will certainly move you. Ginsburg narrates her own story in detail - from the first signs that her life and existence was under threat by the Soviet regime, through her arrest and initial imprisonment in Moscow on trumped up charges, to her first years in the Gulag in Russia's frozen far east.
One slight qualification is that this book ends near the start of her long sentence, as she is adjusting to life in the camps, so there is no description of how she survived and was (as the notes to this volume tell us) eventually released and able to return to European Russia. I would have found that further volume of her autobiography just as fascinating, but at the moment it does not seem to be available in English.