The Innocents (1961)

I was expecting it to be kind of goofy but Jesus that was unsettling. Great plot, fantastic acting. Not about what it initially seemed to be about.

I later learned it was a popular movie at the time that was based on a popular book from the late 1800s.

I looked it up and it was nominated at Canne in 1962, and was nominated for a BAFTA.

I don't know why horror tends to be overlooked, and I'm sure there is a complex and historical answer.