Dr Mabuse was one of cinema's first evil geniuses (he first appeared in Dr Mabuse The Gambler in 1922). His mad staring eyes, white medical clothes and fiendish intelligence (portrayed by the ghoulish Rudolf Klein-Rogge, who also played the mad scientist in Lang's Metropolis) formed a prototype for subsequent larger than life villains, from Blofeld to Dr Evil. It's a measure of the power of his presence that Lang manages to construct this whole film around him: even though he spends less than five minutes on screen and dies in the early stages of the story.
At the end of Dr. Mabuse, The Gambler, Mabuse was sent to prison - and on to a lunatic asylum. Ten years later he's still there, obsessively studied by a psychiatrist Dr Baum (played with real menace by Oscar Beregi) and furiously writing an "instruction manual for carrying out crimes according to irrefutable logic". Meanwhile, a gang of criminals controlled by a mysterious voice that comes from a curtained room are blackmailing, stealing, killing and burning exactly according to Mabuse's manual. A dishevelled but highly effective police inspector, Lohmann (Oscar Wernicke reprising his role from 1931's M with endearingly crumpled charm) picks up the trail - but is thrown off again when Dr Mabuse dies and the crime wave continues.
Cinema historians have long argued over whether this is an anti-Nazi parable. It's certainly
easy to see parallels between Hitler's prison-book 'Mein Kampf' and Mabuse writing insanely in his cell and setting down an agenda to create "The Absolute Rule Of Crime: a condition of complete insecurity and anarchy" - especially given the atrocities of Crystalnacht and the fact that Lang was half Jewish.
Also, this was Lang's last German film before he fled the country and it was one of the first to be banned by Goebbels (who claimed "it posed a threat to law and order and public safety"). Equally, it's possible to view the film as a crime thriller and put the controversy down to coincidence. Lang may have claimed it was about Hitler (in 1943) but he was notorious for making his own myth and exaggerating his anti-Nazi credentials.
Politics aside, this is fine entertainment. The story is enjoyably over-the-top and fast-paced. Right from the very start Lang uses it as a platform for some characteristically extravagant set pieces. The opening sequence is a tense game of hide-and-seek in a warehouse between the criminal gang and a former police officer who's on their trail; the tension steadily notched up by a pounding soundtrack of industrial noises (all the more impressive since this was only Lang's second film using the comparatively new medium). There's a splendidly choreographed assassination carried out at a road junction (we realise it's been a success when the lights change and an aerial camera shows rows of cars driving around the motionless vehicle of the victim), a great race against time in a flooded room.
Not every aspect of the film is a success - some of the dialogue is clunky, much of the acting (heavily reliant on the emphatic gestures and exaggerated facial expressions of the silent era) is alien to modern audiences (although in the case of Mabuse and his mad acolyte Baum this definitely adds to the interest) and there's an unappealing love interest. All the same, the film generally cracks along. The final sequence involving the destruction of a huge chemical works and a car chase through eerily lit woods, round hairpin bends and over a closing level crossing is one of the triumphs of early cinema.