Invisible Strangler tells the story of a boy who strangles his mother and while in a mental institution finds books which give him the key to making himself invisible. He then escapes from the hospital and goes on a murder spree, strangling his mother's friends in a series of unintentionally hilarious episodes, while they sit in their comfortable, expensive homes. The detective assigned to the case, Lt. Charles Barrett (Robert Foxworth) devises an unusual way to dispose of the killer. Sue Lyon, previously seen in Lolita, has a tiny role, as does Elke Somer. Originally shot in 1976 and titled The Astral Factor, this silly, obvious film sat on the shelf for 10 years before being released directly to video