"John Rabe" profiles a man who has been compared to Oskar Schindler, the German businessman and member of the Nazi party who risked his life to save hundreds of Jews from the Holocaust.
Rabe was an executive in China and card-carrying Nazi who had been living in Nanjing, then the Chinese capital, as the head of the Siemens subsidiary there.
The Japanese siege of the city begins in 1937 as Rabe was to return to Berlin. But during the farewell ball in his honour, an air raid sparks a panic and he opens the company gates to offer refuge to his staff and their families.
As the bombardment persists unabated, Rabe orders an employee to locate the giant Nazi swastika flag on the grounds of the Siemens offices. It is quickly spread out like a canopy and dozens of Chinese seek shelter beneath it. The Japanese pilots fly off, recognising that as members of the Axis the Germans should be spared - ending what would have been a bloodbath.
It is a remarkable scene that director Florian Gallenberger told AFP was true to life. "The aspect of a Nazi as a hero was one of the things we gave the most thought to when we made the movie," Gallenberger said after the film was warmly applauded here at its premiere.
"I didn't want to show him in a way that wasn't accurate. After living in China for 30 years, he had a naive, romantic image of National Socialism as an humanistic worker's movement," he said. "I would prefer this to be seen as a film about a human being who displayed civic courage against all odds rather a film about a Nazi. But that was an aspect of his character and it would be wrong to try to cover that up."
Moved by the Chinese plight, Rabe opts to stay in Nanjing and, together with members of the expatriate community, wins the approval of the Japanese occupying forces to create a safety zone for civilians run by the Westerners. Japanese soldiers mount repeated raids in the city, staging mass executions and raping tens of thousands of local women. But up to 250,000 Chinese eventually survive the seven-week onslaught by staying in the safety zone.
Gallenberger said he had never heard of Rabe when his producer approached him with the idea of doing a biopic.
To prepare for the film, Gallenberger travelled to China to speak with survivors of the rape of Nanjing, as the genocidal campaign is known, which ultimately claimed the lives of up to 300,000 Chinese civilians. He said the Chinese authorities were reluctant to allow him to make the movie as the country had little interest in seeing itself as a victim of the Japanese. But they eventually granted him permission.
Ulrich Tukur, who appeared in the German Oscar-winning film "The Lives of Others" leads a cast that also includes US actor Steve Buscemi, French actress Anne Consigny ("The Diving Bell and the Butterfly") and Germany's Daniel Brühl ("Goodbye Lenin").
Though a hero in China, Rabe was until now little known in his native Germany and died impoverished and forgotten in Berlin in 1950. The film-makers also take Japan to task for seeking to wipe the horrors of Nanjing from the historical record.
"It would be great if the film could help start a debate in Japan about this subject because it is not being confronted there," Gallenberger said, adding that he hoped the involvement of the well-known actor Teruyuki Kagawa would ensure broad distribution in Japan.
Gallenberg said that only the passage of time has allowed Germany to look at its own heroes from that shameful era in the country's history.
"The thing about Rabe is that his story is surprising and paradoxical. This confusing image for example of the Nazi flag as a symbol of salvation - which in this instance is historically accurate - is perhaps only possible now at a historical distance," he said.
"John Rabe" is screening in the Berlinale Special section of the festival, which wraps up Sunday.