In the story The Open Window by H.H Munro, how does Munro create an atmosphere of sinister and supernatural?

Saki disrupts the otherwise placid house visit with such strange occurrences as a supposed ghost siting and a tragic death. The open window is the vessel through which this chaos enters the orderly sitting-room scene. The particular type of chaos Saki utilizes in this story is closely related to his fascination with the wild: it involves wild dogs, dangerous terrain, and a forest. Saki commonly uses chaos to mock the customs of English society, preferring the chaotic to the boring order of adult life.