Unlike the other classic masters of crime fiction (Hammett, Chandler, and even Christie if you must) James M Cain wrote not from the perspective of the cop, or the detective, but from the side of the criminal. He wasn't really interested in the methods of detection, but in the methods and reasons crimes were committed.
There are no Phillip Marlowes or Hercule Poirots out to solve the case in Cain's fiction. The righteous bringers of justice are regulated to a secondhand role in his stories, and are often as slimy and unrighteous as the criminals.
In his first novel, The Postman Always Rings Twice, Cain weaves a complicated plot in a very simple manner. This was never meant as anything more than a pulp novel, it's aim was to titillate, shock, and most important of all, sell gobs of books.
Though told in the first person from a main character, the book is all action. There is some internal dialog, but it sheds very little light on who the characters are, what motivates them.
It is in fact, perfect for a screen adaptation. Which is probably why it is credited as the story on at least 5 times on the Internet Movie Database. The lack of complicated internal though processes, and the predilection for talking and doing, makes it the ideal movie. That, and great lumps of sex and violence.
The two most famous screen adaptations are the 1946 Lana Turner/John Garfield version and the steamier Jack Nicholson/Jessica Lange released in 1981. Everyone refers to that one as a remake of the 1946 version which gets me riled up for some reason. To me it is simply another version of the novel, rather than a remake of the old film. There are about 8 million versions of Hamlet out there, but no one refers to the next one as a remake of an earlier film. It's simply another version of the play. But perhaps this is because I'm a fan of the novel, and I probably shouldn't make too big a deal out of it.
The plot takes on several turns but is essentially about lust and violence. Drifter Frank Chambers lands a job at a road side diner owned by Nick Papadakis (Smith in the 1946 version). Chambers falls immediately in lust with Nick's unhappy wife, Cora. They cook up a plot to kill Nick making it look like an accident. Complications ensue.
The biggest difference between the two pictures is that the 1981 version has got more sex. The book is loaded with sex, or should I say simulated sex, or rather off screen (or off page) sex. Due to the prevailing censorship at the time the novel was written the sex had to be hinted at, double entendred and written in such a way as to let everyone know what they were doing and not get banned from book shelves. Even with that, it was still quite controversial at its time.
The 1946 version hints at all the deep seated passion going on without actually showing us anything more than a few kisses. (Though on a side piece of trivia audiences were shocked that Garfield obviously used his tongue in one of the kisses) By 1981 Hollywood was no longer under the strenuous Production Code and morals had loosened up more than a bit through the 60's and 70's and the new version of Postman all the sex was brought out front.
The kissing gets more passionate, there is touching, rubbing and a good deal of nakedness. The steamy sexuality of the characters now scorches off the screen. They even added a new sex scene that wasn't in the book, just for kicks.
But even with all the nakedness and sexing, this newer version doesn't have all the lust of the original. Though Cain was unable to fill in all the sexy details of their affairs, the raw sexuality burns through each page. The characters are led by their passions and you can feel it in every word and deed. In the same way though nary a thigh is even shown in the 1946 version, the passions full of lust are ignited on screen. Turner and Garfield exude sensuality without any sex that far surpasses what Nicholson and Lange can manage with a movie filled with on camera love scenes.
The violence remains pretty much the same in both versions. As a culture, we Americans have always seemed to have less of a problem with violent deeds than any amount of sexuality. Neither film is particularly graphic in its violence, though murder and attempted murder hangs throughout both plots.
My biggest problem with the 1981 version is that first time screen writer, David Mamet, tries to fill out the characters, and give more story to the story. In the book Nick is not a bad man, and we are given no real reason why Cora would be unhappy enough in the marriage to kill. Mamet offers a few small scenes to try to show the darker side of Nick, not enough for the audience to truly hate him, but enough to give some justification for his murder.
Likewise, Frank is a pretty worthless drifter in the novel, but is given a more tender side through the pen of Mamet. Both of these additions serve to lesson the story, not give it greater depth. Cain wrote characters full of selfish lusts. Frank and Cora's passion for each other moves them to do horrible deeds, not out of any love for each other, but for reasons all their own. While it seems admirable that Mamet would attempt to bring human reasons for the characters actions, it only serves to muddle the story. The local news and true crime shelves are filled with real life atrocities committed for no real reason at all.
The 1941 version sticks very close to the novel's plot. There are a few minor changes, I'm sure, and some things left out due to the time restrains of a film. But mostly it sticks closely to the book.
Sadly the great ending of the novel is removed from the 1981 version. This makes the end a little more sad, but the great irony of Cain's closing is all but lost.