"Working in San Francisco as a PI years [after her work in the Spanish Civil War, World War II seems] a world away, but it might as well be on [Miranda Corbie's] doorstep now that she's learned that her mother--whom she hasn't seen in years--is trapped in England. There isn't much she can do until the State Department asks her to keep an eye on a chemistry professor who they suspect is a Nazi spy trafficking in information on allied forces armaments....