When the early photographer William Mumler developed his glass plates, he sometimes found a ghost had slipped into the picture. Was he a fraud? A medium? A grief counselor? Author and curator Peter Manseau explains how Mumler found himself at the crossroads of an emerging technology, and a wave of grief for those lost during the Civil War, and how his spirit photography eventually landed him in court. See the portraits we discuss: P.T. Barnum, by the Mathew Brady Studio ‘Cracked-Plate’ Lincoln, by Alexander Gardner Mary Todd Lincoln, by William Mumler