Secret ceremonies in which malevolent men and women cloaked in hooded robes, hiding behind painted faces and chanting demonic incantations while inflicting sadistic wounds on innocent children lying on makeshift alters, or tied to inverted crosses, sounds like the stuff of which B-grade horror movies are made. Some think amoral religious cults only populate the world of Rosemary's Baby, but don't exist in real life. Or, do they? Ask Jenny Hill.