Generate a question about the following movie plot: The Teutonic Knights invade and conquer the city of Pskov with the help of the traitor Tverdilo and massacre its population. In the face of resistance by the boyars and merchants of Novgorod (urged on by the monk Ananias), Nevsky rallies the common people of Novgorod and in a decisive Battle of the Ice, on the surface of the frozen Lake Peipus or Chudskoe, they defeat the Teutonic knights. The story ends in the retaken Pskov where the ordinary foot-soldiers are set free, the surviving Teutonic knights will be held for ransom and Tverdilo is swarmed over by the vengeful people (and supposedly torn to pieces). A subplot throughout the film concerns Vasili Buslai and Gavrilo Oleksich, two famous warriors from Novgorod and friends, who become commanders of the Novgorod forces and who engage in a contest of courage and fighting skill throughout the Battle on the Ice in order to decide which of them will win the hand of Olga Danilovna, a Novgorod maiden whom both of them are courting. Vasilisa, the daughter of a boyar of Pskov killed by the Germans, joins the Novgorod forces as a front-line soldier, and she and Buslai fight side by side (which makes a strong impression on Buslai); she also personally slays the traitor Ananias. After both Gavrilo and Buslai have been seriously wounded, Buslai publicly states that neither he nor Gavrilo was the bravest in battle: that honor goes to Vasilisa, and that after her came Gavrilo. Thus Gavrilo and Olga are united, while Buslai chooses Vasilisa as his bride-to-be (with her unspoken consent).
The answer to this question is:
What city was conqured by the Teutonic Knights?