The Bletchley Riddle

The Bletchley Riddle (2024) is a middle grade historical mystery novel co-written by Steve Sheinkin and Ruta Sepetys. The novel describes the summer of 1940 in London, with the British defending themselves against Nazi air raids. Nineteen-year-old Jakob Novis and his 14-year-old sister Lizzie, who love riddles and puzzles, find themselves at Britain’s codebreaking factory at Bletchley Park, an operation that is striving to break German communication codes. Jakob works alongside the team to break the Enigma cipher, while Lizzie tries to solve the mysterious disappearance of their mother. All the while, they receive messages and codes on their doorstep while a menacing inspector lurks outside their mansion gates. The novel explores themes of The Nature of Wartime Spirit, The Burden of Secrets, and The Ethics of Espionage.

Sheinkin is a historical nonfiction writer whose titles include Impossible Escape, Fallout, Undefeated, Born to Fly, The Port Chicago 50, and Bomb. He briefly worked in film before moving to textbook writing and eventually authoring graphic and traditional novels, and his books have garnered wide acclaim. In The Bletchley Riddle, he collaborated with Sepetys, a New York Times bestselling author of titles such as Between Shades of Gray, I Must Betray You, Out of the Easy, Salt to the Sea, and more. Daughter of a Lithuanian refugee and winner of the Carnegie Medal, Sepetys writes historical fiction about what she sees as underrepresented stories.

This guide uses the 2024 Simon and Schuster eBook edition.

Content Warning: The source material and guide feature depictions of death, wartime violence against civilians, and antisemitism.

Plot Summary

World War II rages across Europe, and the looming threat of Nazi forces hangs over Jakob and Lizzie Novis. Based in England, they recently lost their mother, Willa, in the violence of the Nazi invasion of Poland, during her assignment to the US Embassy there. The story opens with Jakob, who introduces the reader to the world of wartime espionage with a riddle. He is a 19-year-old mathematician who works at the Code and Cypher School in a secret location in Bletchley Park, England. His work is protected by the Official Secrets Act, and he is isolated from his family and broader society.

Elizabeth, or Lizzie, is Jakob’s sister. She is supposed to board a ship bound for America. She is accompanied by her grandmother’s assistant, Mr. Fleetwood. She slips off the ship at the last possible moment, letting the ship and Fleetwood depart without her. She wants to remain in England to investigate the truth of Willa’s disappearance, as she believes her mother actually survived the Nazi invasion of Poland.

Jakob is shocked to find that Lizzie didn’t return to America. He is sent by his commanding officer, the Colonel, to collect her from a secret postal address in London. Jakob doesn’t hold out the same hope for Willa’s survival as Lizzie does. While stopping off to collect some belongings in their family flat, Lizzie discovers a secret diary/calendar that belonged to Willa under a floorboard.

Jakob takes Lizzie to Bletchley Park. Their relationship is strained due to Jakob’s emotional distance and his preoccupation with his secret work. Despite all the effort and expertise of figures such as Dilly Knox and Alan Turing, the codebreakers are failing to break the Nazi’s Enigma code. At the Park, Lizzie has to sign the Official Secrets Act, and she is then brought to The Shoulder of Mutton, the Inn where Jakob lives. There, she meets the owner’s son, Colin, a mechanic with a passion for the Royal Air Force (RAF). Colin’s brother is serving in the RAF.

Colin helps Lizzie break the lock of Willa’s diary, and they find it is written in code. This, along with mysterious newspaper clippings with hidden codes on them delivered directly to Jakob’s room, hint at a hidden side to Willa and gives clues to her fate.

Jakob trains two new codebreakers, Beyrl and John. He teaches them about the replica Enigma machines they are using and about the sheer mathematical complexity of their operation. They find that they’d need longer than the age of the universe to try every possible combination.

Meanwhile, Lizzie is summoned to the Park, where she is introduced to Marion, a young Austrian Jew, and given a job as a messenger.

All the while, an MI5 agent called Jarvis shadows and consistently interrogates Jakob and Lizzie. He suspects that Willa is alive too, but he thinks that she defected to the Nazis and that her children may know where she is. Lizzie continues her investigations into Willa’s whereabouts, travelling to London and attending an American Embassy party. She discovers that Willa was highly thought of in the embassy and requested a transfer to Poland to help with evacuation efforts.

At the party, Fleetwood returns to take Lizzie to America; however, in a misdirection, Marion takes her place, and Lizzie remains. She and Jakob redouble their efforts to decode the cryptic newspaper clippings.

The Nazi threat intensifies, and England braces for invasion. The codebreakers find something in the encryption that lets them spot patterns in the messages. This, along with Alan Turing’s codebreaking machine, allows them to break the enigma code. This alerts them to the impending Nazi invasion, Operation Sea Lion.

Lizzie finally breaks the code on the newspaper clippings and sets out for London to rendezvous with a person she hopes will be her mother. Jakob follows her by car, and together they find that the Colonel is waiting for them. The Colonel reveals that Willa is alive and a highly regarded MI6 spy who helped Polish cryptographers escape with replica Enigma machines, a vital action. They are sworn to secrecy, as MI6 is going to run with the story that she died in Poland, and she will not see them again until the war is over.

However, a tea lady knocks on the door and sticks her head in. Unbeknownst to the Colonel, Willa has disguised herself and snuck in to retrieve her diary and show herself to her children. Jakob and Lizzie don’t give her away, though they do chase after her after the Colonel leaves. To their disappointment, Willa is gone. After, the Nazi air force bombs London before they can leave, and they hide in a bomb shelter until it is over.

Two months later, the Germans have abandoned their invasion plans, though the Blitz rages on nightly. While the Park was bombed, no one was harmed, and there was no major damage. Jarvis backs off his investigations after receiving the news of Willa’s death, and everyone assembles in the Mutton for a celebration and a toast to the war effort.