Complex sentence: It was the basis for Alfred Hitchcock's suspense film "Marnie" (1964), where the setting was changed from England to the United States, details of the story were changed, and the ending was changed to a more optimistic one.
Split into simpler sentences: It was the basis for Alfred Hitchcock's suspense film "Marnie" (1964), where the setting was changed from England to the United States. Details of the story were changed as well as the ending which was changed to a more optimistic one.