THE DEVIL'S OWN - 1966 - JOAN FONTAINE

An English school missionary assigned in an African village has a run in with the local witch doctor and suffers a nervous breakdown. After recovering back in England she takes a job teaching in a small country town hoping to make a new start for herself. All goes well at first, until she starts to hear some disturbing stories about the town. She soon discovers the town is home to a coven of witches and they plan to sacrifice a local girl in one of their rituals