Hi,
I saw the last half this film on television the other week, but I can't remember if it was on TCM or not. Keep in mind that I didn't get to see it all of the way through, so some of the following may be incorrect.
It seemed to be about a woman (Deborah Kerr?) who's at her husbands ancestral home with their two children. There's some pagan cult and it turns out that all of the males in the family have to be sacrificed to ensure a good harvest/year(s) or something like that. And living at the estate are two creepy siblings-- I think that one of them was the caretaker. But, yeah. They're both very pale and blonde and the brother carries around a crossbow. The sister is a witch or a hypnotist (considering the scene on the battlement).
Uhmm, the wife finds out about the cult and her husbands fate and tries to stop it but it is unsuccsessful and kept locked in a room. She escapes and meets her husbands (thought to be dead) uncle and learns of a way out of the mansion. Uh, stuff happens, the husband dies and they leave. That's all I remember. I'd really like to know the title of the movie, 'cause it was pretty good.