I can't believe that only one user has had a comment on this film after almost 34 years. I remember seeing this film as a undergraduate in 1971. As far as anything goes in 1971, this was as erotic as a film got in that year without garnering an "X" rating. God, life was simpler then. I just watched this film for the first time since 1971 (34 years ago) and every ounce of suspense was still there. Donald Southerland was new to film then and had not yet earned his reputation as the consummate character actor. Jane Fonda had not yet earned the epithet of "Hanoi Jane". And Jean Stapleton was not yet known as "Edit". Although this film seems a little dated as far as acting styles go. The "creep" factor is still there. Anyone who has viewed a few episodes of "Law and Order" will see the obvious villain in the first 30 minutes of this film but will also appreciate the strenuous character development that is evident in the film. Although it is obvious fairly early on who the bad guy is, it's interesting to see the expository effort that is expended in order to flesh out the characters. I am so glad that most of the actors involved in this endeavor went on to greater glory. I thank DARPA for the internet for my ability to inflict my opinions on more than a "small circle of friends".