A photograph—a rare "action shot" documenting a family's murder during World War II—drives a riveting process of discovery for a gifted Holocaust scholar.

In 2009, the acclaimed author of Hitler's Furies was shown a photograph just brought to the United States Holocaust Memorial Museum. The documentation of the Holocaust is vast, but there are virtually no images of a Jewish family at the actual moment of murder, in this case by German officials and Ukrainian collaborators. A Ukrainian shooter's rifle is inches from a woman's head, obscured in a cloud of smoke. She is bending forward, holding the hand of a barefooted little boy. And—only one of the shocking revelations of Wendy Lower's brilliant ten-year investigation of this image—the shins of another child, slipping from the woman's lap.

Wendy Lower's forensic and archival detective work—in Ukraine, Germany, Slovakia, Israel, and the United States—recovers astonishing layers of detail concerning the open-air massacres in Ukraine. The identities of mother and children, of the killers—and, remarkably, of the Slovakian photographer who openly took the image, as a secret act of resistance—are dramatically uncovered. Finally, in the hands of this brilliant exceptional scholar, a single image unlocks a new understanding of the place of the family unit in the ideology of Nazi genocide.