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 great, caped crusaders who 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 as one of the government's special "puzzlers." But an even more top-secret agency has its eye on Josie, along with two other applicants, both of whom share personal experiences that amplify their convictions about justice. When they find themselves transformed into the newest (and youngest!) superheroes in town, this trio will be crucial in thwarting a shapeshifting henchman of Hitler, and, just maybe, in solving an even larger mystery about the missing superheroes.