Whilst there are some key differences between the two versions, the German original follows essentially the same plot as its American counterpart. A group of men answer an ad placed in a newspaper to take part in an experiment, where a prison environment will be simulated. Some of the men take on the role of prison guards, the rest become prisoners. As the experiment progresses tensions between the two sides mount, with Tarek (Moritz Bleibtreu) becoming most influential on the side of the prisoners and Berus (Justus von Dohnányi) taking more and more control of the actions of his fellow guards.
In some ways, I wish I'd seen this original film before watching the 2010 film starring Adrien Brody and Forest Whitaker; in others, I don't think it would have made a huge amount of difference to my view of either film. Das Experiment is the superior film, but it is also quite clear to see the same flaws within it that were transferred to The Experiment.
The performances across the cast are generally strong, with Bleibtreu and Dohnányi providing two solid central characters around which the action can unfold. The cinematography is also effectively used at many points throughout, with a claustrophobic and clinical feel permeating the film. In comparison with the 2010 version, Das Experiment feels the more professional and crafted of the two versions.
There are also a handful of key changes that were made in the remake, with the original feeling the stronger film because they are there. Whereas Maggie Grace had the misfortune of being an entirely forgettable love interest to Brody's Travis, Bleibtreu's Tarek gets involved with Dora (Maren Eggert) in a much more unusual fashion, and she plays more of a part in the unfolding of events than her American counterpart. It's not entirely successful, with some parts of her involvement feeling decidedly confused, but the effort is at least commendable. The role of those running the experiment is also vastly reduced in the American version, giving the German film an extra dimension lacking in the remake.
That said, watching the original makes it clear where some of the fundamental flaws in the remake came from. The psychological element, whilst explored slightly further here, is still woefully underdeveloped. It takes a little longer for things to degenerate into graphic violence and nastiness, but this is due largely to this version of the story being around twenty minutes longer. By the end of the film, I was still left with an unsatisfied feeling and an unsavoury taste in my mouth.
If you were to choose to watch either this film or its American remake, I would advise the German original every time as overall it's the better film. But it's a relative superiority; there are plenty of hard-hitting psychological dramas that are much better than either film, so watch one of those instead.