With virtually no dialogue at all, this is the ultimate observational documentary - with two strands. The first centres around the recreation of a speleological expedition (from 1961) to explore a cave that stretches deep under the Calabrian plateau. The second features an elderly, weather-beaten, shepherd (Antonio Lanza), whose only means of communication appears to be using sounds similar to those emanating from his herd of cattle. It's not immediately obvious at the start, but gradually - and subliminally - the two stories intertwine with a gentle intensity. The cave has something…