“A compelling, fun, and thought-provoking story of magical adventure, coming of age, sacrifice, and family, with secrets that add a lingering darkness to the entire tale.”— Booklist Two young witches, once inseparable, are set at odds by secrets and wildly dangerous magic In the waning days of World War II, with Allied victory all but certain, desperate Nazi diabolists search for a demonic superweapon to turn the tide. A secluded castle somewhere in the south of Germany serves as a laboratory for experiments conducted upon human prisoners, experiments as vile as they are deadly. Across the English Channel, tucked into the sleepy Cumbrian countryside, lies the Library, the repository of occult knowledge for the Société des Éclairées, an international organization of diabolists. There, best friends Jane Blackwood and Miriam Cantor, tutored by the Société’s Librarian—and Jane’s mother—Nancy, prepare to undergo the Test that will determine their future as diabolists. When Miriam learns
