The quiet market town of Wilsnack in northeastern Germany is unfamiliar to most English-speakers and even to many modern Germans. Yet in the fifteenth century it was a European pilgrimage site surpassed in importance only by Rome and Santiago de Compostela. The goal of pilgrimage was three miraculous hosts, supposedly discovered in the charred remains of the village church several days after it had been torched by a marauding knight in August 1383...