Many have panned Robert Mitchum's performance in this film, but I think that his lack of expression and emotion, other than anger, suits the character very well.
Mitchum's Marsh is a completely self-absorbed individual. He's committed to medicine and can't understand human failings, especially his own. His character's cold demeanor perfectly reflects the fact that Marsh has no outer life. If he often appears robotic, it's largely because he's programmed himself to shut out everything human, ironically in service to humanity.
Of course he's a great doctor, but he's pure hell to work or live with. Bursting with pride, insensitive to the point of cruelty, Marsh is unreachable and, in more than one sense of the term, untouchable. Mitchum conveys all of this very naturally, perhaps because so much of his performance is rooted in the dark world of film noir, where the actor first made his mark. He's a physician from the neck up, but he has the heart of a contract killer. That he heals instead of kills is his patients' good fortune, though of little solace to his friends or his wife.
Although Mitchum's interpretation remains controversial, many of the other performances in `Not as a Stranger' are beyond criticism. Olivia deHavilland, as his suffering spouse, is superb as always. Charles Bickford, an actor who deserves a much greater reputation, is the epitome of a small town doctor. And surprisingly, Broderick Crawford is excellent as a gruff professor of pathology.
On the other hand, Frank Sinatra's pediatrician isn't as strong, though he has some good scenes when he tries to help Mitchum see the error of his ways. Gloria Grahame, unfortunately, is stuck with a seductress role that just as well could have been cut.
There are other weaknesses. George Antheil's score, by way of Wagner and Richard Strauss, is pretty hard to take. The script and direction are uneven. Many scenes are compelling, such as when Crawford literally throws the book at Sinatra or when deHavilland and Mitchum have one of their confrontations. Others fall flat and there is a tendency, typical in most of Stanley Kramer's work, to keep making points at the expense of the story. For example, the med school sequences with Whit Bissell's greedy and unethical Dr Dietrich (interesting choice of name there) cover a darker side of the profession very well. There's really no need for Jesse White, terribly miscast as a lawyer who cozies up to Grahame, to bring up ethical issues much later in the film.
Recommended as an above average melodrama and as an interesting time capsule of mid-50s medicine. (Though I found it hard to believe patients were allowed to smoke in the wards!)
