The first part of the film's plot was adapted from a self-titled story published in a 1968 issue of "R. Crumb's Head Comix", while the second part is derived from "Fritz Bugs Out", which was serialized in the February to October 1968 issues of "Cavalier", and the final part of the story contains elements of "Fritz the No-Good", first published in the September/October 1968 issue of "Cavalier". The last half of the film makes a major departure from Crumb's work. Animation historian Michael Barrier describes this section of the film as being "much grimmer than Crumb's stories past that point, and far more violent." Bakshi stated that he deviated from the comics because he felt that the strips lacked depth: