"On the morning of October 21, 1966, Kathleen Middleton, a music teacher in suburban London, awoke choking and gasping, convinced disaster was about to strike. An hour later, a mountain of rubble containing waste from a coal mine collapsed above the village of Aberfan, swamping buildings and killing 144 people, many of them children. Among the doctors and emergency workers who arrived on the scene was John Barker, a psychiatrist from Shelton Hospital,...