Lamestorm
I disagree that this is a film noir. (And yes, I know it's in Silver and Ursini's Encyclopedia.)
The only thing it has in common with noir is a major betrayal and the usual "let's plot to kill him" story line. (It was done better without the gimmicky insanity element elsewhere - Double Indemnity and The Postman Always Rings Twice come to mind.)
It struck me as much more of a run of the mill 1960's Universal style teleplay than a true film noir (or neo noir). It looked and felt too much like, say, a William Castle movie or an episode of Burke's Law than something that could sit beside real noirs.
I found it disappointing. I encounter lots of unjustly neglected and overlooked films - but this one, in my opinion, is justly neglected. Overlong and overwrought.