In March 1941, Osla anonymously publishes the first edition of a weekly gossip column called “Bletchley Bletherings.” One night, Osla goes to the Café de Paris in London to meet Charlie, an old friend on leave. While they are dancing, the hotel is bombed, leaving Charlie dead and Osla unconscious. When she regains consciousness, looters take valuables from her and others. A man comes to her aid, fighting off the looters, and examines Osla, who is in shock, for injuries. When Osla tries to say her name, he asks her if she is Ozma of Oz, a character from Frank Baum’s fantasy series, and promises to help her return to Emerald City. After wrapping his coat around her, he leaves before she can thank him. With the help of aid workers, Osla makes her way to her mother’s London flat. From there, she proceeds directly to a shift at BP, before returning to the Finch home, where Mrs. Finch asks about the man whose initials, J.P.E.C. Cornwell, are written on the coat.

Mab is reassigned to Hut 11 to operate a bombe machine, which is designed to speed up the codebreaking process by discovering some of the settings used by the German encoding machines, called Enigmas.