For centuries it was uncertain what caused the pestilence of 1348, until a vast plague pit was uncovered in Smithfield, London in the 1980s. The find revealed the bones of hundreds of victims of the 14th century pandemic.Now stored in the basement of the Museum of London, Lucy learns how DNA extracted from the skeletons enabled scientists to finally identify a bacteria called Yersinia Pestis - a pathogen to which the mediaeval population had no immunity.In little more than a year, almost half the population had been wiped out by the Black Death. Lucy investigates what this sudden loss of life meant for the church, landowners and for the those who survived.Exploring the social structure of mediaeval England, made up largely of rural peasants indentured to landowners, Lucy discovers a rare and remarkable set of documents: the Court Rolls of the Suffolk village of Walsham the Willows, providing a perfect microcosm of life across the country before, during and after the pandemic.Lucy discovers how, despite the unfolding apocalypse, rather than shaking people's belief in God, it entrenched their faith. Many went on devotional pilgrimages to sacred sites like Canterbury Cathedral.Despite the devastation, the plague propagated a shake-up of the status quo. Workers were in short supply and could demand higher wages, shifting the balance of power. Women occupied professions and roles that were previously closed to them and acquired an independence and status that would previously have been impossible.