Psychologically resounding but bedeviled by somewhat preposterous plot developments, "Das Experiment" is a German thriller loosely inspired by a Stanford University study in which volunteers were placed as guards and inmates in a mock prison to see how they'd interact.

Before the 14-day trial was over, the real experiment went awry with the "guards" becoming power-mad. This film takes this concept to the next level, as one of the "prisoners" -- a former newspaper reporter (Moritz Bleibtreu, "Run Lola Run") trying to get a job-recovering juicy story -- deliberately provokes the reactionary "guards" into a slippery-slope game of domination that soon turns violent and spirals out of control.

The strapping, charismatic, intelligent, expressive Bleibtreu gives a superb performance as he asserts himself among the prisoners -- some of whom don't take well to his rabble-rousing since they just want to lie low and collect the 4,000 Marks they're promised for being guinea pigs.

But with the guards riled up and the professors who are running the experiment ill-prepared to maintain control, push-ups and humiliation punishments soon turn into beatings and worse. Under the usurped despotic direction of a blatantly Hitler-like guard -- a sniveling nobody in the real world who is blindly intoxicated by his power in this "simulation" -- the experiment quickly becomes a nightmare.

Director Oliver Hirschbiegel is successful in creating an unsettling atmosphere in which those trying to stop the experiment are overpowered. But the film's tension is beleaguered by the annoyingly, desperately far-fetched contrivances needed to bring the story to a climax. At a pivotal moment there's only one grad student "on duty" monitoring the experiment, and he forgets to change surveillance tapes. Both professors in charge of this research project are gone -- one of whom is off at some academic tea party in another city, right in the middle of this experiment to which he's supposedly so deeply dedicated.

Plus, to have the last act go down the way it does, Hirschbiegel expects us to believe that 1) the entire campus where the film takes place would be deserted, and 2) not a single guard stops to think what consequences might await him when the experiment is over.

This compounding lack of common sense (along with other, more nit-picky plot problems) eventually overwhelms the movie's provocative mood to such a degree that in the end "Das Experiment" is far more irritating than disturbing.