A disgraced cop named Hofmeister (Karl Meixner), who is still involved in criminal activity, desperately tries to get a message to his former employer, Commissioner Lohmann (Otto Wernicke). Hofmeister tries to tell Lohmann that the notorious Dr. Mabuse (Rudolph Klein-Rogge) is behind the latest crime wave. But Mabuse is now an elderly man who has been in an asylum for years -- Mabuse's hypnotic influence has taken over the mind of the institution's head, Dr. Baum (Oscar Beregi, Sr.)! As Lohmann tries to track down the new mastermind behind the scenes, one gang member, Tom Kent (Gustav Diessl) has a crisis of conscience, mostly to do with his beloved, Lilli (Wera Liessen). Tom and Lilli then find themselves trapped in a warehouse by "Mabuse," with a time bomb ticking away and water filling up the room -- the movie's best sequence. Fritz Lang had already made a long silent film about the German master criminal, Mabuse, and this was his follow-up for the sound era. The film has brief spurts of action and interest -- the murder of Dr. Kramm (Theodor Loos) when his auto stops at an intersection, for instance -- bu it's rather slow as well, and the Commissioner, although well-acted by Wernicke, borders on a buffoon. Mabuse in this is essentially an anarchist and terrorist whose main scheme is to set fire to a plant and unleash poisonous gases on the population. Lilli's reaction to the revelation of Tom's murderous past makes her seem like a sap! There are some flavorful supporting performances in this. Lang followed this up many years later with The 1000 Eyes of Dr. Mabuse. Made in 1933, Testament was not released in the US until nearly twenty years later. A remake made by others was alternately titled The Terror of Dr. Mabuse.
Verdict: So-so Mabuse with interesting moments. **1/2.