'Professor Mamlock' is very much a work of Soviet propaganda, and heavy-handed with it ... not merely extolling the alleged virtues of collectivist Marxism but also viciously condemning the Nazis. In real life, the Nazis were very likely indeed as bad as the fictional Nazis in this movie, but also no worse than the Soviets. Hitler killed millions, but Stalin killed even more.
The title role is performed by Semyon Mezhinsky, who looks like an overfed Gandhi but who emotes like an underfed Werner Krauss.
My IMDb colleague Les 'Longhorn' Adams has synopsised this movie accurately, but his synopsis leaves out some crucial details. Professor Mamlock, a German Jew, has dedicated his life to serving humanity as a medical scientist. However, the rise of Nazism determines that the Jewish doctor cannot possibly be a loyal citizen of Germany: he is therefore stripped of his title and position, and hounded through the streets. Mamlock has spent most of his career at one clinic: now the head of the clinic (a very fine characterisation by Vladimir Chestnokov) beams with approval as racial epithets are smeared (in blood!) across Mamlock's medical tunic while his papers and lab apparatus are smashed. Eventually, the professor is shot dead by Nazi stormtroopers.
About halfway through 'Professor Mamlock', it suddenly becomes clear that the title character is not the movie's real protagonist after all: that dubious honour falls to the professor's son Rolf (Oleg Zhakov), who joins an underground movement of German communists. This being a Soviet movie, it's put forth that communism is meant to be the only possible thing that can vanquish the Nazi movement. Rolf Mamlock ultimately leads a citizens' uprising to defeat the Nazis and instal a communist regime! No comment.
I found the pro-communism scenes in this movie even less watchable than the anti-Nazi sequences, although Pyotr Kirillov is excellent as Rolf's commie comrade. A fine hissable performance is given by Vlad Chestnokov as the Aryan governor of the clinic, who strikes the Jewish doctor's name off the medical register. This deeply hypocritical movie criticises the Nazis for anti-Semitism while ducking the fact that even more Jews were robbed, imprisoned and killed by Stalin than by Hitler.
Isolated bits and bobs of this movie are well done, but on the whole it's extremely bad propaganda, on a level of subtlety somewhere between a bludgeon and a sledgehammer. And that's another reason why the Soviets were even worse than the Nazis. Although plenty of German movies touted the Nazi cause during Hitler's regime, nearly all of them (with a few notorious exceptions) did the job with genuine subtlety, avoiding explicit Nazi symbols in favour of and deference to references to pre-Nazi German scholars such as Friedrich Schiller. My rating for this mess: just barely 2 out of 10.