The Wicker Man
Not the "NOT THE BEES" version, but the vastly more bewitching and less laughable (though plenty campy) 1973 original. A tight-arse policeman (Edward Woodward) searches for a missing child on the estate of the pagan Lord Summerisle (a superbly sinister Christopher Lee) and finds himself at the center of a horrifying plot. Yes, there are plenty of ridiculous moments, like a sexy dance that will have you giggling, but that Shirley Jackson-esque ending still has the power to shake you up. Lhude sing cuccu!