The Bletchley Riddle

During World War II, Lizzie and her older brother Jakob are separated from their mother after she is caught in Poland while working for the American embassy. Though she is presumed dead, Lizzie refuses to accept it. She finds documents hidden in their London apartment and tries to show that their mother is alive. Jakob, a Cambridge mathematics student, works near Bletchley Park on secret efforts to break German Enigma messages. Alternating chapters follow Lizzie’s search and Jakob’s codebreaking work.