Chaos in reverse

What if some books are actually the stories of alternate realities and parallel universes ? Given to authors through time by a magic box that might have been forged by a God once upon a time ?

And what happens then if an actor by accident enters the parallel Universe in which the movie he is about to shoot is the reality ? And he finds out that things are not at all like in the script ?

Disclaimer: I do not own any of the actors or authors mentioned, neither do I own the rights to anything taken from the original story.
And of course those authors wrote their books, they did not get them from magic 😉