A man taking part in a scientific study finds the fine line between play-acting and reality has been blurred beyond recognition in this taut drama. Tarek Fahd (Moritz Bleibtreu) is a journalist who is temporarily making ends meet by driving a taxi when he sees an advertisement offering 4,000 marks to people willing to submit to a psychological experiment. Intrigued, Tarek offers to take part in the study and persuades one of his former editors to help him work up a story about his experiences. Recording the events using a special high-tech video camera hidden in his glasses, Tarek arrives for the two-week experiment to discover half of the volunteers will pose as prison guards and the other half will be their prisoners. Before long the behavior of the subjects suggests more than just make-believe; "inmate" Tarek, in particular, is unwilling to take abuse from the "guards" and makes no secret of his contempt, while Berus (Justus VonDohnanyi) begins playing a dangerous game of cat-and-mouse with Tarek. Tarek, meanwhile, begins escaping reality by fantasizing about Dora (Maren Eggert), a woman with whom he had a brief fling before taking part in the experiment.