The mantrap (1943)

Henry Stephenson stars as a retired Scotland Yard detective. He is regarded as an icon because he has written volumes of books on the art of detection. While Stephenson is being honoured for his past successes, he senses modern detectives, particularly the current District Attorney, look at him and his methods as outdated. This spurs the old man out of retirement to prove himself to the know-it-all modern detectives.