I saw it when it was first on in 1972, and it made a huge impression on me - if I'd never seen it again, the name "Charles, Vermont" would still have stayed with me, and the ending (which I'm not about to give away here). As one person here said, it was one of a wave of weird TV movies from those years, which I made a point of seeing. Any weird TV production from the early ' 70s seems to make me think of "Night Gallery" because of my attachment to that show, but almost none as much as this one. You'd think that it was made by Rod Serling and Jack Laird (or at least one of them), especially that ending. It was like the endings of some apparent fantasy stories (including a few of the Twilight Zones) that explain away the fantasy, but DON'T make you feel CHEATED by their doing that. Martin Landau deserved an Emmy award for his part in it, especially in those last few scenes, with "Virginia" and "Dr. Birdall." And one of the best actors in it was Brock Peters, who (as far as I know) is remembered in a lopsided way, as the defendant in To Kill A Mockingbird. He was very believable as Birdall the psychiatrist, who tries to convince Johnny that he's deluded (withuut being sure of that HIMSELF, since it's partly a "conspiracy story"). And everyone else in it was fine - Jane Alexander, Martin Sheen, Forrest Tucker (another underrated actor, as far as I know).
