-- Milos Forman
This section has been revised and expanded in the new paperback and e-book editions, Playwriting Seminars 2.0.
There's a claim floating around for more years than are worth counting that there are only 10 basic plots in the world. Don't bet on it.
If you reduce the subjects of most plays or films to their most basic elements, whoever started this rumor probably has a point. If you boil the life out of Oedipus the King and end up with "Somebody unintentionally hurts their family" or even more specifically, “A son inadvertently kills his father,” there is a long line of writers who've used this subject, and it can be your turn next.
As a general rule, copyright protection does not extend to the barest bones of a story, but the narrative and dialogue writers use to develop their original versions of these stories is protected. You can't run off to your keyboard with a brainstorm of an orphaned farm boy named Luke Skywalker who gets involved with a princess from another planet and dukes it out with an Arnold Schwarzenegger lookalike whose friends call him Darth. What you can do is a play about a teenager who comes of age by overcoming terrifying odds only to discover his nemesis is his father. Neither you nor George Lucas can get a copyright on that. It’s not much of secret that bits and pieces of images from Frank Herbert’s Dune trilogy float around in the first Star Wars films, but in doing this “borrowing” Lucas and his screenwriter were simply operating in a long and approved tradition of appropriation going all the way back in an unbroken chain to Shakespeare and the Ancient Greeks.
The appropriation that contemporary playwrights do is in most cases not a consciously planned borrowing. The stories, characters, and situations from 2,500 years of dramatic writing are “in the air” and filter into contemporary usage though a process of influence that nearly always disguises the source beyond easy recognition. But there is a far more direct way for playwrights to borrow involving older plays and novels (with some risk): Adaptation.