Most of Saki's adjective phrases in "The Interlopers" advance the idea of conflict between the two main characters, George and Ulrich. Here are several examples:
1. In the opening sentence, Saki describes the setting as a "forest of mixed growth," demonstrating that the woods are so tangled and varied, that it is difficult to tell which part belongs to whom and also to be able to distinguish between friend or foe.
2. In the first and second paragraphs, the author further describes the woods as "dark," as a "narrow strip of precipitous woodland," and "jealously guarded." These phrases add to the idea that the two men's hatred for one another shows the dark side of human nature and that both are walking a dangerous (precipitous) path to letting their hatred destroy themselves.
3. Near the end of the story, the forest is "cold" and "gloomy." The hatred between the two men has dissipated at this point, and they are fueled only by a desire to escape. The gloominess of the blustery, fitful setting portends an unhappy ending for Georg and Ulrich.