A concentration camp survivor confronts one of the most heated and vexed questions of the Holocaust: what price survival? In 1943, sixteen-year-old Paul Steinberg was arrested in Paris and deported to Auschwitz. A chemistry student, Steinberg was assigned to work in the camp's laboratory alongside Primo Levi, who would later immortalize his fellow inmate as "Henri," the ultimate survivor, the paradigm of the prisoner who clung to life at the cost of his own humanity. "One seems to glimpse a human soul," Levi wrote in If This Is a Man, "but then Henri's sad smile freezes in a cold...