The film shares the writing of the diary kept by John Rabe during this time frame and follows his diary as the story line. Rabe (Ulrich Tukur in a brilliant performance) was living with his wife Dora (Dagmar Manzell) in Nanking for 27 years as the head of the Siemens Factory, a German resource for construction in China. They were loyal to Germany, were members of the Nazi party, but lived the good life in the city: Rabe was a compassionate but focused director of the Chinese employees. He is to be retired by the Germans and replaced by a rigid, seemingly evil Werner Fliess (Mathias Herrmann). On the night of his tender farewell party the Japanese attack and it soon becomes apparent that Prince Asaka Yasuhiko (Teruyuki Kagawa) plans to decimate the city. There are others from other nations who are working Nanking - in the university, Valérie Dupres (Anne Consigny), in the hospital, Dr. Robert Wilson (Steve Buscemi), and in the German Embassy, the Jewish lawyer Dr. Georg Rosen (Daniel Brühl) - as well as Chinese aligned with Rabe, Langshu (Jingchu Zhang). When it becomes obvious that the Japanese will slaughter all the populace of the city, John Rabe gathers as many Chinese as he can into a Safety Zone where no soldiers or weapons are allowed, only the support with food and medical attention and beneficence Rabe is able to gather. The atrocities and bombings continue until the very existence of the Safety Zone is vulnerable. Rabe's gathering of the forces around him to protect as many citizens as he can, despite his own gradual physical failure due to his diabetes and lack of insulin, gains him the respect and admiration and love of the people of Nanking.
The film spares no images of the mass executions, the beheadings, and the sexual abuse and torture of the people of Nanking by the Japanese. Much of the film is difficult to watch. But even more tragic is the discovery of the information after the film is complete that John Rabe (as well as Dr. Georg Rosen) returned to Germany as undesirables in 1938 and died in poverty and abandonment by the Germans. The cast is exemplary: many fine cameo roles played by fine actors make this film as touching than the main story. This is a very fine cinematic achievement and deserves a global audience.