Horizon presents a documentary about Multiple Personality Disorder (MPD) where in the 1980's, it suddenly became the talk of the town. Tens of thousands of Americans were diagnosed with an illness that was previously unheard of. A trigger for this su... (more)dden was the release of a film, "Sybil". Telling the dramatic story of a woman diagnosed with Multiple Personality Disorder, the film was shown across America making Sybil a household name.