Copyright law, at least in the USA, views a sufficiently non-generic copy of another work's plot as a copyright violation. For a specific example of how this works, here's a lawsuit based on the concept, and don't miss section 31: http://www.scribd.com/doc/74815749/Angelina-Jolie-Lawsuit (that particular lawsuit didn't succeed.)

Another quirk: copyright law also views copies of sufficiently important elements (like characters/setting/etc. which are clearly taken from another work) as a copyright violation, even if the story is different; fanfic is technically a copyright violation.