We know a lot about the victims of the Great Terror — those who were arrested from 1937-38 by the Stalinist regime and then executed or exiled to the Gulag. However, we know almost nothing about the middle- and lower-level secret police, who carried out these policies and who were later tried in secret. Stalinist Perpetrators on Trial (Oxford University Press) investigates these trials, sometimes referred to as “the purge of the purgers,” through examination of available court documents.