At the start of the memoir, it's 1941 and Eliezer is a twelve-year-old Jewish boy in the Hungarian town of Sighet. He's deeply religious and spends much of his time studying the Torah (the Bible) and the Talmud and praying. His parents and sisters run a shop in the town, and his father is highly respected in the Jewish community. Eliezer begins to study the Cabbala, the book of Jewish mysticism, with an immigrant named Moché the Beadle. When the Hungarian police deport all of the foreign Jews, Moché is sent away, but he returns with a terrible and fantastic tale: the Gestapo stopped the train and slaughtered the deported Jews. Moché escaped with a leg wound and has come to warn the Jews of Sighet to leave. The Jews of the town can't believe what Moché is saying, and think he's gone mad.
The war continues through 1943. In 1944, the Jews of Sighet still don't really believe Hitler intends to exterminate them. Eliezer wants his father to relocate the family to Palestine, but his father says he's too old to start again. The Fascists come to power in Hungary and German soldiers enter the country. Before long, German officers are living in Sighet and then arresting the Jewish leaders of the town. Soon, the Hungarian police round the Jews up into two ghettoes. Next, they force the Jews like cattle onto trains headed to an unknown destination.
The Jews travel on the train for several days, during which time one Jewish woman goes mad and screams about fire. The train arrives at Birkenau, the gateway to the Auschwitz concentration camp, where the passengers can see chimneys belching fire and can smell burned flesh. The women are immediately separated from the men, and Eliezer never sees his mother or his younger sister again (they are immediately sent to the gas chamber). A Nazi SS doctor separates those who are going to be killed immediately from those who will work. Eliezer sticks close to his father. That first night in the camp, he witnesses babies and children thrown into a great fire in a burning ditch. Eliezer's faith in a just God is shattered.
More separations occur, but Eliezer and his father stay together. All the prisoners are tattooed with a number, and this becomes their identity. They are told they must work or they will be burned in the crematoria. They spend three weeks at Auschwitz before marching to another concentration camp, Buna. Here, Eliezer and his father spend their days working in an electrical equipment warehouse. Their Kapo (the prisoner conscripted to wield power over other prisoners) occasionally goes berserk and beats people, including Eliezer and his father. The SS doctor appears again to weed out another batch of people for the furnaces. Eliezer has a scare when his father is chosen, but his father manages to convince someone that he can still work. While at Buna, Eliezer continues to rebel against the idea of a just God. After being forced to witness the slow hanging death of a child, he ceases to believe in God, altogether.
With the front lines of the war getting closer, the prisoners at Buna are evacuated on a long, nightmare death march to a camp called Gleiwitz. People die continuously along the way as the SS forces them to run for hours and hours in the snow, shooting people who fall behind. Upon arriving at Buna, a young Jewish violinist plays pieces of a Beethoven concerto. By morning the violinist has died. The survivors of the march are kept without food and water for several days, more are separated from the rest to be killed, and the remaining prisoners are crammed onto trains in open-roofed cattle cars. The train ride is endless. The Jews have nothing to eat but snow, and people die left and right. When they pass through a German town, some German workers toss scraps of bread in the car to watch the starving prisoners fight to the death. More people lie down in the snow and die when the train at last arrives at another concentration camp: Buchenwald. Eliezer's father grows feverish, contracts dysentery, and begins to waste away. Doctors won't help, the camp doesn't want to waste food on sick people, and Eliezer can only offer his own rations to his father, who is soon delirious. The night before Eliezer's father passes away, an SS officer beats the dying man on the head. Eliezer is unable to cry or mourn. He spends another two and a half months at Buchenwald in a daze before the Nazis begin another prisoner evacuation. This time there is an armed uprising among the prisoners and the remaining SS flee. American tanks arrive, followed by food, although Eliezer gets food poisoning and spends two weeks in the hospital, near death. When he looks at his face in the mirror for the first time since he left the village of Sighet, he sees a vision he will never forget: the face of a corpse.