For sure, but there's a lot more to a film than the plot although if a copy of a plot was too exact one would likely run into problems, depending on how a jury felt about it. I wouldn't feel safe (or justified) taking the script of an existing movie and just rewriting all the dialog, for example.

I came across a good, if somewhat dry, article summarizing the current state of play as regards this: http://www.law360.com/articles/591491/plot-thickens-for-scre...

That exact scenario happened with the film "gravity".

http://www.tessgerritsen.com/gravity-lawsuit-affects-every-w...

That's very interesting, although the page itself points out that it's a breach of contract issue at heart rather than a straight copyright one.

It's still a copyright issue. Despite what people like yourself say, copyright doesn't do a very good job of protecting creators.