David de Jong’s “Nazi Billionaires: The Dark History of Germany’s Wealthiest Dynasties” is a provocative group portrait of five industrialists who expanded their fortunes by colluding with Hitler and then, after World War II, walked away with minimal punishment and barely a dent in their bottom lines. Today these dynasties are worth billions. “Over the past fifty years,” Mr. de Jong writes, “German political leaders haven’t shied away from taking moral responsibility and acknowledging the sins of the past,” not least the atrocities perpetrated during the Nazi regime. Not so these five dynasties, which, over time and across generations, Mr....