Written by Madeline Martin in 2023, The Keeper of Hidden Books is a work of historical fiction that is set in Warsaw, Poland during World War II and follows the protagonist’s development of an underground library in resistance to Nazi occupation. The Keeper of Hidden Books explores the unifying power of literature and the moral complexity of wartime decisions, as well as the value of lasting friendships and shared cultural heritage.

As an internationally bestselling author specializing in historical fiction and historical romance, Madeline Martin is well-known for writing the New York Times bestselling novel, The Last Bookshop in London, which is also set in World War II. She has published over 40 novels, and her works have been translated into 25 different languages. The Keeper of Hidden Books has also been recognized as a 2023 Goodreads Choice Finalist for Best Historical Fiction of 2023.

This guide refers to the 2023 Hanover Square Press paperback edition.

Content Warning: Both the source material and this guide contain descriptions of antisemitism, genocide, and the violence of war.

Plot Summary

In Warsaw, Poland in 1939, Zofia Nowak and her best friend Janina Steinman are high school seniors. In August, as they prepare to start the school year, the threat of war looms large; Hitler has dictatorial control of Germany and has begun perpetrating violence—both physical and cultural—against Jewish people. Zofia and her friends start an “anti-Hitler” book club dedicated to reading the books that Hitler has banned in Germany.

One day, German forces bomb Warsaw, leading Zofia to join her friends and neighbors in sheltering in the basement of her building, along with her mother, Matka, and her brother, Antek. Her father, a doctor, rushes to the hospital to care for the wounded, and the bombings continue for days. Antek, who is only a year or two older than Zofia, leaves under the cover of darkness to join the armed forces defending the city. His family does not know his fate until he returns at the end of the novel years later. In the meantime, they fear the worst.

Zofia and her Jewish friend Janina are members of the Girl Guides. At the urging of their leader, they help with cleanup and rescue efforts around the city. Janina’s grandparents are killed in a bombing aimed at Warsaw’s Jewish Quarter. Soon afterward, the girls’ friend Maria is shot and killed by a pilot while she is helping Zofia and Janina to put out fires. The scout leader assigns Zofia and Janina to help the local library protect and organize the book collections after the bombings. The two girls are familiar with the library staff and take to this assignment readily. While delivering books to the library warehouse, they meet Darek, a charming nephew of one of the librarians and Zofia’s romantic interest.

During several days of heavy bombings, one of the library branches is destroyed. Zofia and Janina join the others sifting through the rubble to look for books. They meet Marta Krakowska, a famous novelist whom they both admire. Warsaw surrenders to the Nazis. The bombings stop, and soldiers enter the city. When school reopens, Zofia punches a classmate in the face in defense of Janina and is expelled. Now that school is no longer an option, Janina and Zofia start working at the library full-time. Two of their friends from the library, Danuta and Kasia, join their “anti-Hitler” book club. Zofia is assigned to work in the library warehouse and becomes familiar with the library’s collection. She also develops a strong relationship with the warehouse librarian, Mrs. Mazur. Because she speaks German, she is one of the first to know when the first list of banned books arrives.

The city changes as the Nazis issue forced work orders for Jewish citizens and require all Jews to wear armbands. Zofia starts escorting Janina to and from work, fearing violence against her friend. Soon, the Nazis fire all Jewish employees from the library. That same day, Zofia returns home to discover that her father has been arrested. For a while, she takes care packages to the prison where she believes he is being held. (She will learn much later that her father is only imprisoned for a few days before he is taken to the countryside to be shot and killed with a number of Warsaw’s other thought leaders.)

Darek stumbles upon their next clandestine book club meeting and asks to join. He also renames the book club the Bandit Book Club. They continue to read banned books and meet in secret throughout the rest of the novel. Zofia joins forces with Mrs. Mazur, the warehouse librarian, to devise a plan to protect the banned books from destruction. They turn over a copy of any books that have duplicates and hide the rest on rarely used shelves. Eventually, they will move books to a secret warehouse off-site.

Janina and Zofia bump into a Nazi soldier while they are running errands. Zofia yells at the soldier, who draws his gun and threatens to shoot them. The encounter is sobering for Zofia; she realizes that she will need to be subtler in her rebellion, so she joins an underground resistance group called the Gray Ranks and begins checking books out of the library to share with Jews.

Janina and her family are forced to relocate to the Jewish ghetto. She continues distributing books to other Jews, carrying a suitcase of books to lend to her neighbors. Zofia asks Matka if the Steinmans can stay with them, but her mother refuses. In mid-November of 1940, the ghetto is sealed; Jews can no longer leave, and other residents of Warsaw can no longer enter. Darek helps Zofia find someone to smuggle a few letters and typhus vaccines to Janina. Janina’s letters describe terrible conditions characterized by overcrowding, starvation, poverty, and the spread of disease.

Zofia attends a secretive school led by her Girl Guide leader, hoping to earn her high school diploma. They disguise the class as an embroidery group and are forced to buy whatever textbooks they can find from an underground bookstore.

Part 2 begins in August of 1942. Janina sneaks out of the ghetto and surprises Zofia one day after work. The friends have not seen each other for a year and a half. Janina is half-starved but remains dedicated to resistance efforts inside the ghetto, so she asks Zofia to find a way to smuggle her parents out. There are now mass deportations taking place, and she does not want her parents caught up in them. She returns to the ghetto the next morning.

Matka helps Zofia to find someone who is smuggling Jews out of the ghetto. Zofia agrees to help the clandestine organization, not just to help the Steinmans but to help others escape as well. On the appointed day, only Janina and her mother arrive. While Zofia is escorting Janina and her mother, a man approaches them and threatens to reveal Janina’s identity. Zofia hits him on the head with a brick, killing him. Janina once again returns to the ghetto, but her mother stays with Matka and Zofia. However, she is not with them long before a neighbor threatens to turn her in. Zofia takes Janina’s mother to the library warehouse as a temporary measure, a tactic that she will repeat with others. Eventually, Mrs. Steinman is successfully placed in a safehouse outside the city.

Library leadership is replaced by two strict Nazi women, and it becomes harder than ever for the librarians to protect their banned books. Zofia and another librarian begin a secret library, loaning books to people from an out-of-the-way library branch. One day, Darek and Zofia attend a secret piano concert. She is moved by the music and by her growing feelings for Darek.

In January of 1943, fighting breaks out in the ghetto as the resistance movement begins its armed uprising. One night, a man appears at Zofia’s apartment with an injured Janina in his arms. She has been shot in the fighting. Zofia and Matka nurse her back to health. Janina and Zofia, along with their other friends, plan to join the fighting when the resistance makes its move across all of Warsaw.

Part 3 describes the Polish Home Army’s battle for Warsaw, which takes place in August of 1944. The library staff prepares the library to be a shelter for people and books. Matka shelters there while Janina and Zofia march to the city’s Old Town to join the battle, led by Darek in his unit of the resistance army. After some early gains, the resistance army struggles to hold their ground against the Nazi soldiers. Darek’s unit suffers losses, and Zofia is shot in the shoulder. Janina accompanies her to the hospital. Once Zofia has recovered somewhat, the two rejoin the fighting but cannot find their unit amidst the chaos. It is days before Darek and Zofia are united. They profess their affection for each other and hope for a future together.

Janina is gravely wounded in a large explosion, and Darek sacrifices himself so that Zofia and Janina can escape into the sewers with a few retreating fighters. They make it out safely, but not many others do, and the Nazis reclaim control of the city. Janina and Zofia shelter in the library with Matka and the other staff while bombs rain down on the city. The Soviet Union forces are finally pushing the Nazis out of Warsaw. Once it is safe, the friends retreat to the countryside and leave the country soon afterward.

Zofia does not return to Poland until 1989, after Soviet control of the country has ended. On her return, she sees Darek’s art displayed in the National Museum and is inspired to write their story.