Beyond Reason (1970) - Australian Movie

Nuclear war breaks out and the staff and patients of a mental hospital take refuge in an underground bunker and accidentally get locked in. Discipline soon disintegrates and the patients, led by Richard, start to resist authority. Richard devises a scheme for a new social order where the sane will take no part. The doctors try to resist but are ultimately overcome. Starring George Dixon, Magie Copeland and Ray Fellow.