A brilliant girl puzzler discovers she’s part of a superhero team!

Josie O’Malley does a lot to help out Mam after her father goes off to fight the Nazis, but she wishes she could do more—like all those caped heroes who now seem to have disappeared. If Josie can’t fly and control weather like her idol, Zenobia, maybe she can put her math smarts to use cracking puzzles for the government.

After an official tosses out her puzzler test because she’s a girl, it soon becomes clear that an even more top-secret agency has its eye on Josie, along with two other applicants: Akiko and Mae. The trio bonds over their shared love of female superhero celebrities, from Fantomah to Zenobia to the Black Cat. But during one extraordinary afternoon, they find themselves transformed into the newest (and youngest!) superheroes in town. As the girls’ abilities slowly begin to emerge, they learn that their skills will be crucial in thwarting a shapeshifting henchman of Hitler, and, just maybe, in solving an even larger mystery about the superheroes who’ve recently gone missing.

Inspired by real-life women from World War II—the human computers and earliest programmers called “the ENIAC S...