Sara Ackerman writes historical fiction set in Hawaii, and The Codebreaker’s Secret takes place during World War Two at Station HYPO, the naval intelligence operation that helped break Japanese codes. The protagonist is a young woman cryptanalyst whose presence in a male-dominated unit is itself a small constant friction.
A secondary timeline set decades later involves a journalist trying to piece together what really happened to a missing wartime colleague. Ackerman alternates between the two periods.
The research is thorough. The historical detail of life in wartime Honolulu, the technical challenges of cryptanalysis, and the social rules around women in uniform all feel grounded.
For readers who liked Kate Quinn’s The Rose Code or any of Pam Jenoff’s WWII novels, this fits the same shelf. Ackerman’s earlier Hawaii novels also deserve attention if this one lands well.