Read the excerpt from "The Adventure of the Mysterious Picture."

The expression was that of agony -the agony of intense bodily pain; but a menace scowled upon the brow, and a few sprinklings of blood added to its ghastliness. Yet it was not all these characteristics-_it was some horror of the mind, some inscrutable antipathy awakened by this picture, which harrowed up my feelings.
What effect does the tone of the excerpt have on the reader?

The tone of the excerpt is ominous and unsettling, creating a sense of fear and unease in the reader. The description of agony, menace, and horror evoke a feeling of dread and anticipation of something sinister or malevolent. The use of words like "agony," "ghastliness," and "inscrutable antipathy" heightens the sense of foreboding and mystery, leaving the reader intrigued but also apprehensive about what is to come.