The Crimean peninsula, strategically important located in the Black Sea, has been a favorite place for militaries for centuries. Above all, the Crimea opens the access to the Mediterranean Sea. But the Crimea not only offers a good military location, but is ideal for cave construction. Over the centuries, residents and the military have taken advantage of this over and over again. The Soviet Union, in particular, made considerable efforts to secure the area after the Second World War.

In the documentary we discover the underground secrets of the Crimea and search for clues in the abandoned bunkers, caves and catacombs. Whether a hidden shipyard for nuclear submarines in the Bay Balaklava, the Inkerman catacombs under the city of Sevastopol or the "Sonderkombinat No. 1", an underground heating station with bunkers for storage of coal and engine rooms - together with so-called diggers, explorers of the underground, we venture into the underworld of the Crimea, where experts help us to understand the context and the importance of buildings in the past and their possible use in the future.

45 Min./52 Min. Arte, ZDFinfo