From the first chapter: "The great challenge in writing a feature-length screenplay is sustaining audience emotional involvement from page one through 120. Most writers can dash off a ten or fifteen minute script with little planning; as the length stretches to an hour or more, it becomes difficult both to conceive a script in its entirety and execute the individual scenes at the same time. Most professional writers use various tools to solve this problem - writing a treatment, outline, step outline, be eat sheet, or using file cards. The function of all of these is to allow writers an overall view of their work while they toil away at the specific scenes. " The author suggests that breaking the script down into sections he calls 'sequences' will allow scriptwriters to complete their task. He discusses his process in detail and gives examples from many films. An excellent book on screenwriting - one of the best.