I saw this in its rebroadcast in March of 1978 at age 15 when I was on spring break during my freshman year in high school. How the plot would unfold was a real mystery throughout much of the film, which kept me interested. Had I known how creepy it would actually get even before its climax, I might have turned it off, but I was hooked. The creepiest part actually occurs before the end of the film. The ending just leaves the viewer sort of hanging because nothing is resolved one way or the other. (Has the invasion of earth begun, or were the dire warnings about the alien's intentions mere fabrication?) The alien Marc actually seems so sincere about his love for the young girl. I wasn't totally sure whether his intentions were evil or not but I suspected that they were. He actually seems like a nice gentleman at first. Yet, in the middle of the film, another cast member (an unlikable character himself) warns the young girl that Marc's intentions are sinister. At the end, I found myself hoping that he could perhaps be reasoned with about the possibility of peaceful co-existence with our dimension. If not, we were in trouble because their technology was evidently way ahead of ours!