This film is more commonly known as The Invisible Strangler, and that pretty much tells you the plot of the movie. Most sources date this as a 1976 film, but others as a 1984 film. Let's spilt the difference and call it a 1980 film, but I lean towards 1984 myself.
A convicted strangler has studied the paranormal and has learned a way to make himself invisible. He sets out to eliminate the five women whose testimony put him away behind bars. It's a police procedural with very little procedural. After the first crime, the police figure out who he is because even invisible men leave behind fingerprints.
This movie is full of familiar faces. Robert Foxworth (Falcon Crest, The Questor Tapes) plays the lead police detective, Stephanie Powers (Hart to Hart) plays his wife, and Elke Sommer (A Shot in the Dark) plays a potential victim. Sue Lyon (Lolita, Evel Knievel), billed third in this film, dies 30 seconds after the opening credits end.
It's pretty cheesey. All these poor actresses spend most of their limited screen time pretending that they are getting beat up by an invisible attacker. In fact, the killer, played by Frank Ashmore (V, Airplane!), has only a few minutes of visible screen time himself.
Most of the actors acquit themselves reasonably well, but this is nothing more than cheap formula drek. At times, the film doesn't even look finished as sometimes the colour timing is way of whack, the picture drops out, and one part of a scene is in black and white for some inexplicable reason. It looks like this DVD was mastered off an old workprint -- there's scratches in the film indicating where cuts were still to be made.
On the bright side...no, I'm lying. There is no bright side.