The story focuses on the following elements:
* The isolated, decaying manor house: The setting of Stoke Moran contributes to the atmosphere of isolation and suspense. The dilapidated condition of the house adds to the sense of unease and mystery.
* The locked room: The sealed bedroom where Helen Stoner sleeps, and the locked room where the snake is kept, create a sense of confinement and danger.
* The hidden passageway: The secret passageway leading from the vacant room to Helen Stoner's bedroom highlights the manipulative nature of the killer and increases the story's suspense.
* The presence of the snake: The deadly snake is a powerful symbol of danger and violence. Its arrival in the room is described as a terrifying event.
The presence of a snake, and not gypsies, is a crucial element in the story's plot and thematic exploration of deception, fear, and the darkness that can lurk within the human heart.