"It's set up for many sequels because the book is so dense with information and historical references, and it's an international story. There are so many things we could do with this - if it works. But we need this one to work - which we think it does," Pitt said.
Pitt, who played main character Gerry Lane and also produced the film, is confident the first movie can lead to a franchise because there are so many possible talking points that come up in it.
"I'm so fond of this film, because there are many interpretations that start arising. And I love that it starts that kind of dialogue, but more than anything, it's just the most intense thing you're going to see all summer," he added.