The story of Stalin’s terror is well known, except for one dimension: the fate of those among the tormentors who were themselves swept into the meat grinder. This “purge of the purgers,” as Viola terms it, came after Stalin called off the Great Terror in 1938. Those who had carried out the two mass operations in 1937–38 against former “kulaks” (supposedly well-off peasants), foreigners, and “anti-Soviet” and “socially dangerous” elements—sending almost 1.5 million people to either the gulag or execution—were themselves put on trial. In 1939, nearly a thousand of them were arrested; many were subjected to torture—the very crime for which a lot of them were being tried. After elaborate trials, they were either sentenced to death or the gulag or sent to the front during World War II. Viola draws from Ukraine’s secret police archives—which, unlike Russia’s, are open—to detail how the accused defended themselves, the testimony against them, and the outcomes. As well as lifting the cover from this less well-known part of the story, Viola explains in great detail the interaction between what was commanded from above and what flowed from forces at the ground level.