Read the excerpt from "The Adventure of the Mysterious Picture." I began to undress, but in spite of every effort I could not keep myself from stealing a glance every now and then at the picture; and a glance was now sufficient to distress me. Even when my back was turned to it, the idea of this strange face behind me, peering over my shoulder, was insufferable. I threw off my clothes and hurried into bed; but still this visage gazed upon me.
What effect does the tone of the excerpt have on the reader?
It fosters a belief that the narrator is unreliable.
It encourages surprising delight in blood and gore.
It inspires confidence that everything will work out fine in the end.
It produces shivers down the spine, or a feeling of unease.