Tony Cornell spent his life probing the very edges of reality. A member of the UK’s Society for Psychical Research (SPR), Cornell’s role as an investigator of so-called “spontaneous cases” saw him returning time and again to the unsettling spaces that exist just on the periphery of our ordered, tidy, and rational lives, and which we all do our best to ignore: Ghosts. Spirits. Premonitions. Psychic powers. Glimpses of other worlds that throw into question everything we take for granted about life, death, and material existence itself.

This is a gripping narrative drawing on Cornell's casefiles, which survive as a huge and uniquely untapped repository of stories reported by ordinary people, as well as correspondence between some of the great intellectuals of the 20th century—including Sir Arthur Conan Doyle, Mark Twain, Winston Churchill, and Marie Curie. By applying logical rigor to the investigation of events that could not be explained by conventional science, the SPR drew notable figures to its ranks as it gathered the most meticulous records ever compiled on hauntings, spiritual possessions, and other enduring mysteries. Award-winning journalist Ben Machell mines the extensive archives of the SPR for the first time to reveal the untold history of the secretive organization, and to understand our interactions and ceaseless fascination with the unexplained.