We hear interesting casting stories out of Hollywood all the time. Harrison Ford, a carpenter by trade, was reportedly hanging a door for Francis Ford Coppola when he got his big Star Wars break. Bill Murray makes people call an 800 number when they want him for a project. The way Ben Affleck got the lead in Gone Girl, however, is a casting story for the digital age. Director David Fincher says he cast Affleck by Google Image–searching his smile. Fans of the book will know that Fincher wasn’t after a million-watt movie-star smile. As the director told Playboy:

You cast movies based on critical scenes. In Gone Girl there’s a smile the guy has to give when the local press asks him to stand next to a poster of his missing wife. I flipped through Google Images and found about 50 shots of Affleck giving that kind of smile in public situations. You look at them and know he’s trying to make people comfortable in the moment, but by doing that he’s making himself vulnerable to people having other perceptions about him.

For those unfamiliar with the book, Fincher included that “critical scene” in the Gone Girl trailer. Affleck’s best “I didn’t kill my wife grin” looks a little something like this:

Is that the smile of an innocent man? In the same interview, Fincher goes on to discuss the theme of public perception that runs throughout both the book and the film. He draws a comparison to Scott Peterson, a man whose uneasy demeanor made him guilty in the public eye long before he was actually convicted of murdering his wife. But the more interesting comparison Fincher draws is to Affleck’s own life experience as someone who has been in the spotlight for the past 17 years. He explains: