But, if the art of filmmaking is inseparable from that of adaptation, it’s because almost all feature films are made by way of a fundamental form of adaptation: that of a script. Filmmakers who survived in the studio system often figured out how to effect changes beyond what their studio minders would grant. There’s a delightful secret history of Hollywood directors whose ruses and stratagems bought them an unusual amount of leeway with their scripts. In film after film, Robert Siodmak leveraged small script tweaks into major revisions. downright massacred Orson Welles’s Booth Tarkington adaptation, “The Magnificent Ambersons,” both slashing the film that he’d made and encumbering it with rewritten scenes shot by someone else.