Four young urban explorers from the United States, South America, Asia and Europe meet up in Berlin via internet to explore the subterranean relics of Nazi Germany. The destination for the illegal tour, through a labyrinth of tunnels, sewers and catacombs, is a special bunker, the ''Fahrerbunker'' (Adolf Hitler's subterranean garage) which is the center of many legends, where they expect to find the debris of forbidden Nazi mural. But when tragedy strikes the group's leader, they soon realize not all things go according to plan.