In late March 1944, as Stalin’s forces push into Ukraine, young Emil and Adeline Martel must make a terrible decision: Do they wait for the Soviet bear’s intrusion and risk being sent to Siberia? Or do they reluctantly follow the wolves—murderous Nazi officers who have pledged to protect “pure-blood” Germans? The Martels are one of many families of German heritage whose ancestors have farmed in Ukraine for more than a century. But after...