Made by Granada TV in 1969, it’s almost impossible to believe that this adaptation of Alan Garner’s cult children’s novel was intended as a kid’s series. Set in a remote Welsh valley, where three teens from unhappy families find themselves helplessly replaying an ancient legend, it’s bold and eerie, marked by spare location shooting, abrupt editing, a class war theme, unbearable undercurrents of sexual tension (the teens are played, quite discomfitingly, by actors ten years older), and an absolute refusal to explain its mad mysteries. Astonishing.