A weekend subway shafts and sewers? A few young tourists (Nathalie Kelley, Nick Eversmann, Brenda Koo, Catherine de Léan) want to explore the hidden world of Berlin’s underground. The city guide of a different kind (Max Riemelt) promises them a not quite legal journey to the driver’s bunker, Adolf Hitler’s chauffeur’s quarters. When Kris falls, two set out to get help. A young American and his girlfriend stay with the injured man. Out of nowhere, the weird Armin (Klaus Stiglmeier) suddenly appears, a former East German border guard. In desperation, they accept his help and transport their now unconscious guide to Armin’s quarters. The nightmare has just begun…