In May of 1944 the author, a Hungarian Jewish physician, was deported with his wife and daughter by cattle car to the Nazi concentration camp, Auschwitz. This memoir chronicles the Auschwitz experience, and the German retreat, ending a year later in Melk, Austria when the Germans surrendered their position there and Nyiszli obtained his freedom. The author describes in almost clinical detail and with alternating detachment and despair what transpired in the crematoria and the dissecting room during his tenure as chief pathologist working directly under Dr. Josef Mengele.

From the first, Nyiszli suspected that there were horrors emanating from the crematoria but he singled himself out from a group of physicians by deciding to "[break] ranks" when Mengele asked those with forensic training to identify themselves. This act secured his survival: the remaining physicians, none of whom stepped forward, all soon perished, while he was assigned to the Sonderkommandos--the prisoners who carried out the exterminations, and who were themselves regularly exterminated to prevent the truth from becoming known. He writes, "As chief physician of the Auschwitz crematoriums, I drafted numerous affidavits of dissection and forensic medicine findings which I signed with my own tattoo number."

At times self-congratulatory about his forensic expertise, at times forcing himself to witness atrocities which he could have avoided, occasionally finding a way to delay death for some of the inmates, Nyiszli was determined to record what he saw--to bear witness, were he to survive. Uncannily able to read a situation and take advantage of it, the author relates how he managed to get his family out of Auschwitz just before they were scheduled for annihilation. Even in the final weeks of the war, when he and thousands of prisoners trudged on foot for weeks with the retreating German army, many dying along the way, he remained shrewdly assertive--and lived.