Have you ever felt scared, uneasy or seen something in the corner of your eye that you can't explain?

Well, in theory many of us have, but have either chosen to ignore it and put it to the back of their minds, or taken up the challenge to explore it further.

Could it be a ghost or is there a reasonable explanation for this mysterious feeling when one attempts to to enter the spirit-world through investigation or through contacting a spiritualist medium to get answers?