... it would probably all be like Children of the Stones.
This is perfection on a silver disc.
Very few old TV shows completely live up to fond childhood memories. Production values, fashion, acting styles have all changed so much. It's almost miraculous that this vaguely science fictional "young adult" equivalent of the Wicker Man stands up to repeat viewings now. It really does deserve that over-used title "a genuine classic".
The hero is a teenage boy whose astro-scientist dad is investigating the strange properties of the stone circle that surrounds a too-perfect English country village. He quickly notices that everyone except newcomers are just too spookily happy with their lot. He makes friends with the two other "normal" teens in the village, and a mad old tramp, but it's soon clear that the threat of becoming blissed-out zombies hangs over them all.
It's classically claustrophobic and suspenseful without being "old fashioned" (except, ironically, for the fashions). The race against time to discover the secret of the always-too-suspicious lord of the manor is even scarier because almost everything happens in daylight.
The golden age cast includes Iain "Budgie" Cuthberston, Gareth "Blake's 7" Thomas and Freddie "unsung genius" Jones. If you like this try to track down comedy series The Ghosts of Motley Hall, which has dated but now exudes period charm.)
Genuinely not for very young children. Ideal for middle aged post-youths.