The films took many liberties from its source material. Granville's portrayal of Nancy showed her as a ditzy and absent-minded schemer, in contrast to the books of that time, where Nancy was intelligent, sharp-tongued, and quite ahead of her time. Carson Drew of the books was portrayed as an older, feeble, hands-off parent, while John Litel's Carson was young, handsome, much more athletically fit, and tried his best to restrain Nancy from getting into danger. Ned/Ted was even more drastically altered: instead of being Nancy's boyfriend in college who lives in a different town, he was now her clumsy next-door neighbor, who was often in the center of Nancy's scheming unwittingly or under protest. The recurring character of the older Hannah Gruen was replaced with Effie Schneider, Hannah's teenage niece who had appeared in the book the first film was based on. Effie and Hannah's characteristics were merged, although Effie's fidgety, frightful nature retained prominence for comedic effect. In addition to these four, the new character Captain Tweedy was added, to portray the stereotypical bumbling, clueless cop that mirrored Steve McBride in the "Torchy Blane" series. The characters of Bess Marvin, George Fayne, and Helen Corning did not appear in the film series, and were never mentioned or referred to.