Hannibal Rising

In 1941, an eight-year-old Hannibal Lecter lives in Lecter Castle in Lithuania. Hitler's invasion of the Soviet Union turns the Baltic region into part of the bloodiest front line of World War II. Lecter, his younger sister Mischa, and their parents travel to the family's hunting lodge in the woods to elude the advancing German troops. After three years, the Nazis are finally driven out of the countries soon to be occupied by the Soviet Union. During their retreat, however, they destroy a Soviet tank that had stopped at the Lecter family's lodge looking for water. The explosion kills everyone but Lecter and Mischa. They survive in the cottage until five former Lithuanian militiamen, led by a Nazi collaborator named Vladis Grutas, storm and loot it. Finding no other food in the bitterly cold Baltic winter, the men look menacingly at Lecter and Mischa.
By 1949, Lecter Castle has been turned into a Soviet orphanage and is ironically housing the interned orphan Hannibal Lecter. After dealing violently with a bully, Lecter escapes from the castle orphanage to Paris to live with his widowed aunt, the Lady Murasaki. While in France, Lecter flourishes as a student. He commits his first murder as a teenager, killing a local butcher who insults his aunt. He is suspected of the murder by Inspector Popil, a French detective who also lost his family in the war. Thanks in part to his aunt's intervention, Lecter escapes responsibility for the crime.
Eventually, Lecter becomes the youngest person ever admitted to medical school in France. He works in Paris, where he is given a job preparing cadavers. One day, Lecter witnesses a condemned war criminal receiving a sodium thiopental injection, allowing him to recall details about his war crimes. Consequently, in an attempt to recall the names of those responsible for his sister's death, Lecter injects himself with the solution. His subsequent flashback reveals to the viewers the men who had killed Mischa, had also cannibalized her as well. Lecter returns to Lithuania in search of his sister's remains. He excavates the ruins of the lodge where his family died, and upon finding Mischa's remains, he gives her a proper burial. He also unearths the dog-tags of the deserters who killed his sister. One of them, Dortlich, attempts to kill him but is incapacitated by Lecter. After he buries Mischa's remains, Lecter forces Dortlich to reveal the whereabouts of the rest of his gang, then decapitates Dortlich with a horse-drawn pulley. Dortlich's blood splashes on Lecter's face, and he licks it off.
Lecter then visits Kolnas' restaurant in Fontainbleau. He finds his young daughter and notices Mischa's bracelet on her. He gives her Kolnas' dogtag. Dortlich's murder puts the rest of the group on alert and, because of the similarity to the first murder, places Lecter under renewed suspicion from Popil. Grutas, now a sex trafficker, dispatches a second member of the group, Zigmas Milko, to kill him. Lecter kills Milko instead, drowning him in formaldehyde inside his laboratory. Popil then tries to dissuade him from hunting the gang. During a confrontation with Lady Murasaki, she begs him not to get revenge, claiming that he made a promise to Mischa. He attacks Grutas in his home but Grutas is rescued by his bodyguards.
Grutas kidnaps Lady Murasaki and calls Lecter, using her as bait. Lecter recognizes the sounds of Kolnas' birds from his restaurant in the background. Lecter goes there and plays on Kolnas' emotions by threatening his children. Kolnas gives up the location of Grutas' boat, but Lecter kills him when Kolnas goes for Lecter's gun. Lecter goes to the houseboat. In a final confrontation, Grutas claims that Lecter too had consumed his sister in broth fed to him by the soldiers, and he was killing them to keep this fact secret. Enraged, Lecter eviscerates him by carving his sister's initial into his body. Lady Murasaki, finally disturbed by his behavior, flees from him even after he tells her that he loves her. The houseboat is incinerated, but Lecter, assumed to be dead, emerges from the woods. Lecter hunts down the last member of the group, Grentz, in Canada.

Question: Why did Hannibal's family flee their home?
Answer: To avoid the Nazi invasion.