Sara Ackerman (Radar Girls) provides a fast-paced, lushly described historical adventure in her fifth World War II novel, The Codebreaker's Secret. After losing her beloved brother, Walt, at Pearl Harbor, codebreaker Isabel Cooper accepts an assignment in Hawai'i to help defeat the Japanese. There, she navigates brain-bending codes as the only woman in "the Dungeon," an underground bunker staffed with brilliant men none too thrilled by her presence. Two decades later, Luana Freitas, an ambitious young reporter on assignment at a swank Hawaiian hotel, becomes a friend of a hotel guest who goes missing. Lu, with the help of veteran photographer (and former flyboy) Matteo Russi, digs into the mystery, uncovering some secrets that may connect the missing guest to Isabel--and put Lu herself in danger.
Ackerman skillfully shifts back and forth between her narratives, creating two female protagonists who are both driven and compassionate. Isabel's deep grief over her brother's death conflicts with her joy at making friends with Matteo and savoring Hawai'i's natural beauty. Both Isabel's efforts to be fully accepted by her fellow cryptanalysts and Lu's struggle to figure out what she wants from her journalism career feel achingly timely. Meanwhile, both women are also wrestling with more personal desires, even as the war (for Isabel) and the events at the hotel (for Lu) pull them in different directions than expected.