The Lost People (movie, 1949)

Set in a German theatre after the Second World War, two British soldiers are holding a disparate and hostile band of refugees in this theatre, prior to returning them to their homelands. The soldiers have difficulty dealing with the rivalries between Serb and Croat, resistance fighter and collaborator, Pole and Russian, etc. The threat of plague briefly unites them, but eventually even this wears off and the refugees unite in their hostility to the British.