The novel

This is one of those movies (and stories) that lasts in your mind. The movie is based on the novel The Flowers of War by Geling Yan, a well known Chinese writer who's a member of the Hollywood Writer's Guild of America and the Writer's Association of China. It was published in 2007 and is based on true events that took place during the Nanjing Massacre in 1937. What was it? it was the time when the Japanese forces invaded the Chinese city of Nanjing, slaughtering soldiers, raping and murdering civilians and doing all kind of horrible things. The novel, of course, adds some fictional events and characters, but the Massacre was real.
The Film tells the story of John (Christian Bale), a corpse make-up artist who arrives at a Catholic church in Nanking to prepare the parish priest before his burial. When he gets to the church compound, which is supposedly neutral territory, discovers the priest's body has been blown up by a bomb and suddenly, after getting drunk with wine, he finds himself sheltering a group of schoolgirls who live there, after he defends them from Japanese soldiers. Then, a group prostitutes from the floating brothel nearby climb over the compound wall and demand to be hidden and protected from the war. And later, the situation becomes even more intense when a wounded Chinese soldier appears.

Official Movie Poster for China

All of these characters trust in the guide of Father John and even when he doesn't want that at first, as the movie moves forward he becomes more and more commited with the girls's protection and then with the risky attempt of their salvation.
After an incident when Japanese forces assault the cathedral, Colonel Hasegawa promises to protect the convent by placing guards outside the gate (turning the refugee into a prison) and requests that the schoolgirls sing a chorale for him at a party. Knowing what may happen to them at that party, the schoolgirls decide to commite suicide by jumping off the cathedral tower, but in the last minute they're saved for the prostitutes, who are willing to protect them by taking their place at the Japanese party.
The story is full of humanity - at its worst and at its best - because it shows the drama of war (the scenes between the soldiers are incredibly good) and the cruelty of the Japanese soldier's abuses (some scenes are really rude and violent) but on the other hand is the work of John, who decides to save the girls, to protect them even when at the beginning of the story he was nothing more than a drunk make-up artist; and of course, the prostitutes with their ultimate sacrifice show there's more to see than meets the eye and that we can't judge people so quickly, their sacrifice brings them honor. When they arrived to the compound, everyone thought they would be perdition for those innocent schoolgirls, but living together and making plans to fool Japanese soldiers bring them together as sisters.
Violent, dramatic, strong, sad, but with a bittersweet ending full of hope, The Flowers of War is a movie that everyone should see.