The Glass Key is a well-regarded film from 1942, based on the novel by Dashiell Hammett, first published in 1931 (it appeared in serial form the previous year). The screenplay was written by Jonathan Latimer, himself a crime novelist of distinction, Latimer's later film scripts included the masterly The Big Clock, based on Kenneth Fearing's equally fine novel, and Night Has a Thousand Eyes, based on a characteristically compelling Cornell Woolrich story.
The central character is Ed Beaumont, played by Alan Ladd. He's the right hand man of Paul Madvig (Brian Donlevy), a rascally political fixer who throws his weight behind the election campaign of Ralph Henry after falling for Henry's daughter (Veronica Lake). She, however, is more interested in Beaumont, who does the decent thing and rebuffs her advances.
When Beaumont finds the body of Henry's son, who has been playing around with Madvig's sister, Madvig is the prime suspect. Madvig has earned the enmity of a local gang boss, who has Beaumont badly beaten up, but although Madvig behaves ungratefully, Beaumont continues to show considerably loyalty. Commendable as this is, I could have done with more insight into the reasons for Beaumont's devotion, given that he's not a closet gay character.
The plot continues to thicken, and the film is watchable from start to finish. Beaumont isn't a private eye, but he plays the detective and solves the mystery to everyone's satisfaction. He even gets the girl. I find it rather sad to reflect that both Ladd and Lake, two charismatic actors, died relatively young. This is a good film which deserves its reputation,,although the book is even better, and so are The Big Clock and, arguably, Night Has a Thousand Eyes. To say nothing of The Maltese Falcon.