In the wake of the Civil War, Spiritualism--and its promises of communication with the dead--reached its peak as grieving families hoped to reunite with men lost in battle. In the face of an uncertain future, people sought comfort in the messages of mediums, and for Philadelphians, that reassurance was found in Katie King. Katie was a spirit who materialized at the seances of Mr. and Mrs. Nelson Holmes--or so attendees believed. For eight months in...