Anxious to explore the mysterious hidden world under metropolitan Berlin, an international group of four urban explorers hires a local guide, Kris, who leads them into the maze of escape tunnels and subterranean fortifications under the city. When their guide has a bad fall, two of the girls in the group frantically set off to seek help while Denis, the young American, stays behind. Armin, a former East German border guard suddenly appears from nowhere. Out of sheer desperation, Denis allows Armin to lead them and their unconscious guide to safety and it is at this moment that Denis realizes he has just made the biggest mistake of his life!
More implied than shown, there is a graphic description of male rape, during which they force him to wear a wig, then later a male character is forced to wear a wig.
Lots of comments are made along the lines of "you thought you were alone down here". The main antagonist follows one character onto a train and convinces a stranger to believe him over the other character.