I thought I had read that Mystic River wasn't the first film based on the novel, and that the two films went in separate directions from the original storyline. One focused on the "detective vs. suspect" plot, while Mystic River downplayed the detective's role and emphasized Sean Penn's character as a developing mob boss. Am I mistaken?

Len

I can only find one film adaptation of Mystic River.

Here are links to the wikipedia articles about the book and the film. Perhaps this will help clear up any confusion.

Mystic River (novel) - Wikipedia, the free encyclopedia

Mystic River (film) - Wikipedia, the free encyclopedia

The plot synopsis from IMDB (Internet Movie Data Base): Mystic River (2003) - Synopsis

I am sorry I misunderstood your question. I thought you were asking if there was a previous film adaptation of the novel Mystic River.

I had hoped that the fact that the wiki for the novel mentions no other film adaptations would answer your question about there being another film based on the novel. Also, the book was published in 2001 and the film was released in 2003 which pretty much means there wasn't time for a previous version of the novel to have been released on film.

Good luck finding the information you are actually looking for.