Imagery is a literary resource to represent physical senses. When you read a text, you are able to feel it in a realistic way. It helps the reader to understand better the setting.
An example of imagery in the story is in the line "when something like a heavy footstep was heard without, rushing down the steep side of the mountain" This is an example of auditory sense, it appeals to our sense of hearing. In this case this image lets the reader to know what kind of sound the characters heard. It is a sudden and dry sound that alerts them.
