Located in the amazing rocky and narrow insides of the Ligurian mine of Gambatesa (which after the economic crash has been transformed into an ecological museum) this movie is freely taken from the short story Impostor by sf American writer Philip K. Dick. In a gloomy and uncertain future, Spence Olham is suspected to be an infiltrated enemy aiming at destroying the community and so chased by his own fellows. Going up and down the eight mine levels, Olham has a face to face encounter with his best friend who literally lets him down, into the void. After a dreadful plunge into a huge underground lake, Olham tears down toward the dramatic unexpected ending, revealing his impostor nature and the paradox of a double identity. This film is the outcome of a very personal point of view of an author who did not waver, helped by the miners, to let himself down the sometimes dangerous depths.