Wrede is back, with a magical alternative history set in the Columbian West, some years after the Secession War. Unlucky 13th child Eff moves with her loving family—professor father, stoic mother, older siblings not yet on their own and her twin, Lan, the 14th child and the seventh son of a seventh son—to a land-grant college on the banks of the Mammoth River, along which runs the Great Barrier Magic that keeps steam dragons and other monsters safely at bay. Eff tells her tale in leisurely fashion, relating the events big and small of her growing up: Lan’s advanced magic lessons, her friendship with fellow faculty child William, sister Rennie’s elopement with an anti-magic Rationalist—and, perhaps most importantly, her tutoring sessions with Miss Ochiba, who teaches her not only Avrupan but also Hijero-Cathayan and Aphrikan magical techniques. The world-building is effortless, flowing naturally through Eff’s conversational narration. The culminating adventure of this volume—an expedition to investigate a plague of destructive grubs—ties up Eff’s coming-of-age with a frontier-style bow while leaving her poised for more adventures—many more, readers will hope. (Fantasy. 12 & up)