Kirkus
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Siblings decode familial and wartime secrets in 1940 England. Headstrong 14-year-old Lizzie Novis refuses to believe that her mother, a U.S. embassy clerk who was working in Poland, is dead. After fleeing from her grandmother—who’s attempting to bring her back to America—Lizzie locates her 19-year-old brother, Jakob, a Cambridge mathematician who’s stationed at the clandestine British intelligence site called Bletchley Park. Hiding from her grandmother’s estate steward, Lizzie becomes a messenger at Bletchley Park, ferrying letters across the grounds while Jakob attempts to both break the ciphers generated by the German Enigma machines and help his sister face the reality of their mother’s likely fate. With a suspicious MI5 agent inquiring about Mum and clues and codes piling up, the siblings, whose late father was “Polish Jewish British,” eventually decipher the truth. Shared narrative duties between the siblings effectively juxtapose the measured Jakob with the spirited Lizzie. Lizzie’s directness is repeatedly attributed to her being “half American,” which proves tiresome, but Jakob’s development from reserved to risk-tolerant provides welcome nuance. The authors introduce and carefully explain a variety of decoding methodologies, inspiring readers to attempt their own. A thoughtful and entertaining historical note identifies the key figures who appear in the book, such as Alan Turing, as well as the real-life bases for the fictional characters. Interspersed photos and images of ephemera help situate the narrative’s time period. A rich, enthralling historical mystery that engages and educates.(Historical mystery. 10-14) Copyright © Kirkus Reviews, used with permission.