Ideas can't be copyrighted. There are only seven basic plots (plus or minus depending on who does the categorizing) and they have all been done thousands of times, so there is no copyright on a plot, else every author in the world would be sued every time they published a book. You can't copy characters and you can't take large excerpts or strings of original wording verbatim from other works, but you can certainly rearrange them to your own version of an old story.
A case in point which I thought would surely go to the plaintiff, but didn't, was when the authors of Holy Blood Holy Grail (non-fiction) sued Dan Brown over The Da Vinci Code (fiction). Having read Holy Blood Holy Grail first, I thought that Brown had taken quite liberally from the text of that book. Large areas of quoted research were very similar as well as the basic premise of Jesus' blood line continuing after having a child with Mary Magdalene. The courts ruled in Brown's favor. Of course someone could probably point out a different outcome for other suits, but if you use your own words to recast a story, you should be on fairly safe ground. That is not to say that someone couldn't bring a nuisance suit to try to deter you. Take care. Vern
Edited for PS: As stated in the Copyright Act: In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work.
