Answer:
In the story "The Interlopers" by Saki (H.H. Munro), the appearance of Georg Znaeym is unexpected because he is the enemy of the main character, Ulrich von Gradwitz. The two men have been feuding for years over a piece of forest land, and the sudden appearance of Georg on Ulrich's side of the forest at night would have been a surprise to Ulrich. This unexpected appearance ultimately leads to a tragic turn of events in the story.