Lucas's initial treatment, partly inspired by Joseph Campbell's "The Hero with a Thousand Faces", contained a few key scenes that made the final film: Luke would study the Force under a Jedi master (then named Minch Yoda) before dueling Vader and ending up hanging from the bottom of a floating city, and the gambler would betray Han to Vader. As Harrison Ford had not agreed to appear in a third film, the character of Han Solo was written out of the ending by having him go off to secure funding for the Rebellion. During his discussions with Brackett, Lucas conceived the title, "The Empire Strikes Back", and the idea to have it follow a structure akin to his film "American Graffiti" (1973)—one main plot with three subplots. Lucas envisioned 60 scenes, a script around 100 pages, and a roughly two-hour runtime. The two laid out the film's basic plot, but also discussed expanding the character of Han—with Lucas suggesting that he met Chewbacca because he was raised by Wookiees—and Luke's lost twin sister.