Writing in his autobiography, Peet decided to write a screenplay before producing storyboards, though he found the narrative "complicated, with the Arthurian legend woven into a mixture of other legends and myths" and finding a direct storyline required "sifting and sorting". After Walt received the first screenplay draft, he told Peet that it should have more substance. On his second draft, Peet lengthened it by enlarging on the more dramatic aspects of the story, which Walt approved of through a call from Palm Springs, Florida.