Differences between the 1898 novella Turn of the Screw, by Henry James and the 1961 film, The Innocents, directed by Jack Clayton mostly have to do with characters, but the variations make a world of difference in the effect of the movie. The biggest discrepancy between the two is the age of Miss Giddens. In the novella she is very young. She is described as being nervous for her first real job and as a young woman in her twenties; she needed to think over the job carefully before accepting it. Deborah Kerr, who was about forty, plays Miss Giddens in the film; and the first thing noticed is that she is not all that young after all. The woman in the movie seems to have had some experience with children and even expresses some maternal instincts.
Because Miss Giddens is not what most expect when brought to life on the big screen, it is more than a little comforting that the children are exactly what was expected and more. Martin Stevens and Pamela Franklin are exactly the children depicted in James's novella. We first meet Flora, who is portrayed to be so angelic that it is downright creepy. Even before the idea that ghosts exist, viewers are "creeped out" with how much fun she has in the tub and how charming she is when she first meets her brand new governess. That girl is so well behaved in front of Miss Giddens one has to assume she misbehaves when she is not around her governess.
Martin Stevens takes the uneasiness viewers get from Pamela Franklin and takes it to the next level. His smile makes skin crawl, and the kiss he lays on Miss Giddens will makes anyone's stomach churn. The more he tries to act like a grown up, especially when he is left alone with Miss Giddens in the end, the more uncomfortable he makes the viewers. He leaves everyone unsure about whether he is seeing Peter Quint (performed by Peter Wyngarde) or just trying to stay out of the way of his crazy governess.
Without the outstanding performances of the two children in the film The Innocents, the overall story as James tells would be lost. Their performances make the ending so confusing. No one is really sure who was seeing ghosts, if the ghosts were real, or who was still sane. If there were mediocre actors in the children's roles, it would be undisputable that Miss Giddens is imagining the presences and the children are victims of her imagination. However, the children make this movie scary because they do indeed raise the possibility of the ghosts being real.