How much do we REALLY know of ghosts? Few and/or a bit? Well, do you recall the movie "The Others" with Nicole Kidman in the main role?
Imagine you have the ability to see and communicate with ghosts, what would you do? Or the opposite, how is it to be a ghost? Cold and frightful or confused and agressive... (No matter how the ghosts are good or bad but keep the rate in PG-13 level.) You are also allowed to use historical facts that has inpired you or true experience.
(P. S. If you need ideas about ghosts check out the TV-series "Most Haunted" or "Supernatural".)
Have fun! ^.^