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, in Shrewsbury. At Aberfan, Barker became convinced there had been supernatural warning signs of the disaster, and decided to establish a "premonitions bureau," in conjunction with the Evening Standard newspaper, to collect dreams and forebodings from the public, in the hope of preventing future calamities. Middleton was one of hundreds of seemingly normal people, who would contribute their visions to Barker's research in the years to come, some of them unnervingly accurate. As Barker's work plunged him deeper into the occult, his reputation suffered. But in ...