For ordinary people the word caving conjures up darkness, cold and dampness, mud traps and underground rocks, almost a nightmare. There are however some people who feel at home in this hostile world and are prepared to accept whatever it has to offer, whether good or evil. The Mania for Depth is perhaps the first film which studies the concept of this unusual relationship and films the heart of this world, alternating interviews with scenes of exploration in an abyss in Switzerland.