The novel is set in Budapest, Hungary, during World War II. After Nazi Germany invaded Hungary in March 1944, the Arrow Cross, a Hungarian political party modeled on the Nazi Party, rose to power and imposed severe restrictions on Jews, forcing them to wear yellow stars, live in designated buildings or a ghetto, and closing their businesses.
The story opens on November 5, 1944, with an unnamed 13-year-old boy huddled in a crowded freight car, consumed by guilt. A week earlier, he began making plans to reconnect with loved ones he was forced to erase from his memory six years prior, but his efforts have landed him on this train of horrors.
The narrative shifts to October 30, introducing the boy as Hendrik Varga, a student at the Franciscan Assisi School in Budapest. Brother Ferenc, a Franciscan friar, announces that the boys will prepare for the Catholic sacrament of confirmation, calling it their "gateway to manhood." Hendrik and his best friend, Ivan Biro, nudge each other with excitement; the two have spent the summer hoping to become the youngest Arrow Cross members. Ivan's father, Sergeant Biro, is a prominent Arrow Cross officer.
Brother Ferenc's lesson, that parents once made decisions for the boys but now the choice will be theirs, triggers forbidden memories. Hendrik recalls his childhood on the Pest side of the Danube: his mother's singing, Sabbath candles, and family gatherings with Aunt Mimi, Uncle Peter, and cousins Gabor and Lilly. In 1939, Uncle Peter was sent to a forced labor camp, and Hendrik's father announced the family would assume false Christian identities. He obtained forged papers and a new home in Buda, insisting that Hendrik never speak of their Jewish past. Their Catholic housekeeper, Magda, accompanied them. Ivan's friendship made forgetting easier.
Stirred by Brother Ferenc's challenge, Hendrik resolves to find his relatives in the Budapest ghetto and learn about his Jewish heritage. When Ivan announces he will spend Saturday with his father and forgets to invite Hendrik, Hendrik sees his chance.
On November 4, Hendrik cycles to Pest carrying pilfered food. Gunshots erupt behind him at the bridge after Arrow Cross soldiers turn to deal with a group of rounded-up Jews. He recognizes childhood landmarks but notices yellow stars on buildings and boarded-up storefronts. He climbs an oak tree to enter the ghetto without passing through the guarded gates.
The squalor shocks him: Emaciated people beg in doorways, and children are too weak to play. He locates Aunt Mimi's apartment above a cobbler's shop. Aunt Mimi embraces him, and Lilly, now thin and traumatized into near-silence, steps forward. Aunt Mimi explains that Father's money could only cover false identities for his immediate family and that she now sees he made the right choice. Hendrik gives Lilly his sweater and leaves the food.
Aunt Mimi urges him to leave before afternoon patrols, but outside, Hendrik collides with Sergeant Biro. Overwhelmed by anger, Hendrik reclaims his birth identity: "I'm not Hendrik. I'm Jakob. Jakob Kohn. And I am a Jew." Sergeant Biro orders Jakob, Aunt Mimi, Lilly, and others arrested. Gabor grabs the barrel of a gun pointed at his mother; a soldier shoots him dead. Jakob is forced onto a truck. Sergeant Biro orders Ivan, watching from the shadows, to alert patrols to arrest the Varga family. Ivan exchanges one glance with Jakob, salutes his father, and runs off. Jakob interprets the silence as betrayal.
At Budapest's Eastern railway station, Jakob is shoved into a cattle car. During the journey, he glimpses Lilly wearing his sweater, being led away from the train alongside Aunt Mimi. Believing they are about to be shot, he covers his ears and shuts his eyes, missing a rescue attempt. Only later will he learn that Raoul Wallenberg, a Swedish diplomat saving Hungarian Jews through false documents and safe houses, intercepted the train and freed Aunt Mimi and Lilly but could not find Jakob.
The train arrives at Auschwitz, the vast network of Nazi concentration and death camps in occupied Poland. Jakob lies about his age, claiming to be 16, and is deemed fit for labor. He is stripped, shaved, and tattooed with the number 18036.
Jakob befriends Aron, an older boy from Debrecen who teaches him the camp's survival economy, and uses his hatred of Ivan as fuel to endure. Levi, an Orthodox Jewish young man from Mako, is assigned to share Jakob's bunk and becomes his spiritual teacher. He instructs Jakob in Hebrew prayers and values such as
tzedakah, the obligation to help the poor. When SS officers, the Nazi paramilitary force running the camp, discover Levi's singing voice, they provide extra food, which Levi smuggles back to Jakob and Aron. On Hanukkah, the Jewish festival of lights, Jakob steals a candle from a supply truck, and Levi leads inmates in the traditional blessing.
The camp's Kapo, a Jewish prisoner named Szekeres appointed by the SS to manage the barrack, regularly humiliates prisoners by forcing them to fetch his baton on all fours. On December 31, the Kapo selects Levi. Levi refuses, declaring that God made him a man and he will walk with dignity. An SS officer shoots him dead. That night, Jakob covers Levi's body and recites the Kaddish, the Jewish prayer for the dead.
When Jakob and Aron are transferred to Blechhammer, a satellite work camp, Jakob discovers two SS corpses in the rubble and strips them of their uniforms. At dawn, the boys dress as officers, commandeer an unattended patrol car, and bluff their way past the exit barricade. They abandon the car near a forest and spend weeks traveling on foot through Poland and Slovakia until Russian Allied soldiers find them. Jakob shows his tattooed arm, and the soldiers shelter and feed them. They learn Auschwitz was liberated on January 27, 1945.
After months at a displaced persons camp in Austria, the boys part at the Hungarian border. Jakob arrives in Budapest in early May 1945 to find his former apartment in ruins. At a Red Cross compound, he spots Ivan serving soup in a food line and attacks him. Ivan, bleeding, reveals that Jakob's parents, Aunt Mimi, Lilly, and Magda are all alive, and that Ivan helped save them.
Ivan explains that the ghetto's horrors shattered his desire to join the Arrow Cross. When his father ordered him to alert the patrols, Ivan instead ran to Brother Ferenc, who told him to bring Jakob's parents to the monastery. Ivan reached the apartment first and led the family through a tunnel the boys had discovered years earlier. Brother Ferenc contacted Wallenberg, who moved them to a protected house. Ivan joined Wallenberg's underground network. When the Germans retreated in February 1945, Ivan refused to flee with his parents and has not seen them since.
Jakob and Ivan each ask and grant forgiveness. Ivan takes Jakob to his parents' apartment, where Mother embraces him. Father privately apologizes for not trusting Jakob with the truth, and Jakob apologizes for his actions in the ghetto. In the weeks that follow, Jakob struggles with flashbacks but finds solace studying Jewish tradition at a synagogue. Brother Ferenc encourages his plan to have a bar mitzvah, the Jewish coming-of-age ceremony. Aunt Mimi, who tells Jakob she does not blame him for Gabor's death, announces that she and Lilly are emigrating to Canada.
On August 28, 1945, Jakob stands before the congregation for his bar mitzvah. He chants from the Torah, the sacred Jewish scripture, looking out at his family and a small gathering of survivors. He imagines the empty seats filled with those who perished and sees Levi among them. His eyes meet those of Brother Ferenc and Ivan at the back. The passage speaks of the choice between life and death, blessings and curses, and the exhortation to choose life, echoing the lesson that set the story in motion and affirming Jakob's embrace of his Jewish heritage.