It tells the story of a journey in the waning months of World War II concerning the Emmerich family, who flee their beloved home in Prussia and move west to avoid the advancing Russian troops.

Bohjalian said in an interview he was inspired to write the story after being persuaded to read a diary spanning from 1920 to 1945 belonging to Eva Henatsch, a German woman that embarked on a similar journey west across the Third Reich.

The plot of the story centers around a young Prussian girl, Anna Emmerich, and the broken remnants of her family as they flee westward from the advancing Russian army.

As Anna, her mother, her younger brother Theo, and Callum trek across the Third Reich, other stories run parallel to theirs, including the story of Uri Singer, a Jew that leapt off the train to Auschwitz and survives by assuming identities belonging to various German soldiers; and Cecile, a French Jew taken prisoner in a concentration camp and, along with her fellow prisoners, forced to march westward to outdistance the Russian advance.

Eventually all three stories come together when Anna's party, joined by Uri, crosses paths with the sad march of Cecile and the other prisoners.