Born in Oklahoma to parents who immigrated from Germany in the 1960s, veteran journalist Bilger grew up eating Bratkartoffeln and Gurkensalat, immersed in German traditions, and speaking the southwestern German dialect of his parents' hometown in the Black Forest region. Outside the house, however, Bilger avoided talking about his heritage, sensing that his Germanness marked him as automatically suspect in the eyes of others, the specter of World War II always lurking. People would size him up warily, asking his parents' age and silently calculating back to 1939. More than one acquaintance confessed that it had taken them time to overcome their initial distrust, given his background. "To be German, it seemed, was always to be one part Nazi," Bilger writes, "In my case, that part was my grandfather."

Bilger was 28 when his mother first told him that her father, Karl Gönner, had ...