Watched this film about three times when it was shown on TV in the UK. Probably in the late 60's and early 70's. I loved it then and still do.
The cast includes many celebrated actors, TV stars and one notable TV presenter.
Margaret Rutherford was awarded an Oscar for her part. David Frost, popular journalist and TV presenter of the day, made a cameo appearance as a newspaper reporter.
Elizabeth Taylor, Richard Burton, Orson Wells, Rod Taylor and a very young, (I was smitten), Maggie Smith were among the rest of the cast.
There are no action scenes, car chases nor special effects. Yet the story develops a growing tension as each sub-plot is revealed.
Highly recommended should you be looking for an antidote to the super hero genre.