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?