Endpapers excavates the extraordinary histories of the author's grandfather and father: the renowned publisher Kurt Wolff, dubbed "perhaps the 20th century's most discriminating publisher" by the New York Times Book Review, and his son Niko, who fought in the Wehrmacht during World War II before coming to America.

Kurt Wolff was born in Bonn into a highly cultured German-Jewish family whose ancestors included converts to Christianity. Always bookish, Kurt became a publisher at 23, setting up his own firm and publishing Franz Kafka, Joseph Roth, Karl Kraus, and many other authors whose books would soon be burned by the Nazis. Fleeing Germany in 1933, a day after the Reichstag fire, Kurt and his second wife, Helen, sought refuge in France, Italy, and ultimately New York, where in a small Greenwich Village apartment they founded Pantheon Books. But Kurt's taciturn son Niko, offspring of his first marriage to Elisabeth Merck, was left behind in Germany, where despite his Jewish heritage he served the Nazis on two fronts.

As author Alexander Wolff visits dusty archives and meets distant relatives, he discovers secrets that never made it to the land of fresh starts, including the connection between Hitler and the family pharmaceutical firm E. Merck, and the story of a half-brother Niko never knew.