Adult novelist and scholarly author Davidson crafts a YA alternate-history/murder-mystery romp—and mostly pulls it off. In a world in which Napoleon won Waterloo, it’s 1939 and the Federated States of Europe and the New Hanseatic League have concluded one war but may be poised for another. Sixteen-year-old Sophie finds herself in the midst of political intrigue after a medium delivers a cryptic message and then turns up dead. The medium’s death is just the start: IRYLNS, founded by Sophie’s great-aunt and guardian, transforms girls into perfect secretaries via a sinister process; Sophie’s chemistry teacher may be masterminding suicide bombers; and spirits seem set on communication. The world-building sometimes falters and thinking too hard about the changes may confuse readers (how did Freud become a radio personality, and why is he fixated on Daedalus?), but despite the flaws, who can resist a spunky heroine, political machinations and a disembodied Alfred Nobel? Readers willing to dive in will be eager for the sequel. (author’s note) (Fantasy/alternate history. 13 & up)