the film's main plot is the same as the book. however, a few things in the novel are not in the movie. some subplots and backstories are not in the film. for instance, johnny fontane and lucy mancini are more developed in the book. the book also gives a background to the villain jack woltz. the childhood of vito corleone is not in the film. in the book, johnny fontane goes to hollywood. in the end, kay corleone accepts michael as the new boss over the family. she realizes how heartless her husband is.