When there is a lengthy flashback comprising more than half of the text, a frame story is the portion outside the flashback. For example, Mary Shelley's "Frankenstein" uses the adventures of a sea captain as a frame story for the famous tale of the scientist and his creation. Occasionally, an author will have an unfinished frame, such as in Henry James's "The Turn of the Screw". The lack of a finishing frame in this story has the effect of leaving the reader disoriented, adding to the disturbing mood of the story.