Actually, I had a choice of early, eerie Peter Weir puzzlers for this slot, but since I already sang the praises of shivery Aboriginal-themed thriller “The Last Wave” in a previous Halloween-themed list, I thought I’d instead go for a film that veers much further from conventional definitions of horror: a slow-burning, open-ended mystery revolving around the inexplicable vanishing of a group of Australian schoolgirls, plus their teacher, on a class field trip. The ensuing hysteria among the remaining characters is very nearly as chilling as the enigma of the disappeared.