Gone Girl is quickly becoming one of the most anticipated films of 2014. Part of the hype is due to the source material: Gillian Flynn’s New York Times bestselling novel, while those who have not read the book are anxiously awaiting another David Fincher thriller featuring a noteworthy cast. On top of all this, Flynn (who is adapting her own novel for the big screen) recently announced that the film will depart from the book in the final act in what will amount to a wildly different ending.

In the interest of preserving the plot twists (if you haven’t read the book, do it!), the following will have to suffice as a summary. When Amy Dunne (Rosamund Pike) goes missing on her 5th wedding anniversary the evidence begins to implicate her husband Nick (Ben Affleck), and he gradually becomes the prime suspect.

Flynn’s novel deeply examines the dichotomy of love and anger in Nick and Amy’s troubled relationship and explores the causes of decay in once happy marriages. Other themes in the book include dishonesty, economic recession, and the effects of the media on society.

While the plot and themes will carry over, Flynn reports that the film will tell the story differently than the novel. This is in part due to the new ending; however, the non-linear structure of the book also makes for a tricky film adaptation, and could be altered somewhat to better accommodate the translation. While the story unfolds from Nick’s perspective, Amy’s absence requires her voice to be heard through diary entries that span the length of her relationship with Nick.

The beauty of Flynn’s announcement is that audiences can read the book without fear of ruining the surprise once the film hits theaters on October 3.