Built in 1890, the Imperial Theater stands on one of the small islands dotting the Ohio River. A vast, ornate, crumbling pile of brick and mortar, it abounds in fantastic architectural details and decades of history.   And ghosts. They are waiting for the curtain to fall.   Locals know the Imperial is not a good place to visit after dark. But to make their dream of having their own theater company come true, Joanna Marshall and her friends will go as far as renovating the landmark building. And what better way to celebrate its revival than to open with a dark, horrific play that draws on its sordid history?   If only Joanna's terrifying dreams would stop. If only she had let the dead rest in peace.