After viewing the film and reflecting on what made the film tick, my kudos do not go to the actors, who appear to be the backbone of the film, but to a solid script and screenplay.
For the first half hour the movie seems to be making inane statements about bringing up children. But those early conversations become meaningful after the movie is over as the choices the father makes have much to do with the parallels in teaching the son early lessons in life--"stealing" planks from your parents' bed to make a toyhouse is to be viewed in comparison to "stealing" stockholder wealth to regain personal property.
At another level, the story is a mirror of Job's dilemma--standing steadfast on principles when all his earthly possessions (including his wife) are being taken away. It is to the credit of the script and the director that the tormentors (the kidnapers) remain unseen and the battle is merely relegated to one man's internal moral turmoil.
Was Glenn Ford's performance creditable? Yes and no. At the end of the film you tend to think it was a memorable performance. But think of replacing Ford with any good star of the day and the effect could have been much the same, thanks to the script.
I feel this was a good film because it did not lapse into trivial confrontation with the kidnapers as most contemporary movies do. It was good because the film avoided pitfalls, while adding color to fringe characters by providing them with short punchy lines such as the lines of the school headmistress, the journalists, the ice-cream vendor, the pedestrian who wonders how speeding police cars don't get tickets, and last but not least the Afro-american butler.