Karl Tonezzer, a “Kaiserschützen” (a member of the Austro-Hungarian Imperial Infantry) of 1915, and Sibir, his dog, “re-emerge” from history and from the bowels of the mountain. That is when the forgotten epic deeds of Trento fortress also re-emerge. The construction is an extraordinary defensive system built in few months by the Austro-Hungarian army and thousands of civilians at the beginning of the Great War. On Trento Mountains the soldier and his dog walk along the war tracks and tracks where volunteers and forest rangers unearth trenches, batteries in cave and casemates. The past history of an impregnable fortress, mostly underground, interweaves with today’s stories and memories of men and women who have adapted the war artefacts to civilian life. Karl and Sibir discover that the invisible fortress, probably forgotten because nobody ever fired at its walls, has come back to life, and that indeed it had never disappeared.