Most "Ghosts" are the products of an agitated imagination. A bat in the attic... a moss-draped tree limb swaying in a moonglow fog... even a harmless household pet can be mistakenly translated into a midnight spook if the conditions of one's imagination are set in a frightened mode.
But, sometimes, there is more at work than logic can explain. Sometimes --when your skin crawls and your heart begins to race-- spirits may be present and up to mischief... or worse.
Ghosts are real, but they may not be what you think they are...