they had an ambitious idea and tried to make it work.... it was rather cringe at times and the acting wasn't the best but the idea was interesting.

Double personalities in a tangled script. Suspense.

John Lithgow improved his craft years later in Dexter but unfortunately his acting was terrible in this, only masked by all the other terrible acting in this flick. Felt like a live theatre performance and would have better suited a 1950s Hitchcock attempt where the audiences were more forgiving.