A brief rundown of the plot is in order: We meet Walter Neff (Fred MacMurray), as he literally shuffles into his office. He turns on his Dictaphone; his coat falls back, and we see a hole in his shoulder. He begins to record a message for his boss, Barton Keyes (Edward G. Robinson), regarding a recent insurance claim: "you said it wasn't an accident, check. You said it wasn't suicide, check. You said it was murder... check." And thus begins Walter's "confession" of the murder of his client, Dietrichson (Tom Powers) and his torrid affair with Dietrichson's wife, Phyllis.
Edward G. Robinson was also not originally thrilled to be playing Keyes. Robinson had spent his career since Little Caesar playing the lead. Now, though his name was still above the title, he was third billed, and playing a character part to MacMurray's leading man role. However, his willingness to take on a character part paid off well. He is outstanding as Keyes - smart and interesting. A lesser actor would have not had the power to threaten Walter's complacency over his perfect crime. Robinson, who had long played overpowering men (despite his diminutive size), continues to do so with this cagey insurance executive. His importance as an actor within the genre of film noir is undeniable. After Double Indemnity, he would go on to impressive performances in such noir classics as The Woman in the Window, Scarlet Street, and The Stranger (where he again chose the character part to great effect).
The current ending of the film was not the one written by co-author Raymond Chandler. Originally, the film would have ended with Walter's execution in the California gas chamber, but following previews the scene was cut - over Chandler's vocal objections (A scene in which Phyllis and Walter commit suicide was also written, but was rejected and never filmed). The Production Code Administration's Joseph Breen found the execution scene "unduly gruesome", and Wilder did not feel that it matched with his vision of the film, so it was excised from the picture. Though lost, production stills of the scene survive.
And then, there is Stanwyck. She is amazing as Phyllis - beautiful, smart, passionate, but cold and calculating. Watch her eyes as her husband dies in the car seat beside her - you can see into her soul in that scene. The Modern Times blog discusses Stanwyck's concerns with the role - her fascination with the character, and her fear that she - who had never played such a whole-hearted villain before - was not equipped to play the complex part. Luckily, Billy Wilder thought otherwise, and he again was able to get the right actor for the right part. To me, her most interesting scene is the death of her husband, but the second scene that comes to mind when talking about the film is her descent down the staircase, her leg adorned with a gold anklet. RogerEbert.com has an interesting article that discusses the anklet, which was not a part of James M. Cain's original story. The addition of the anklet provides insight into both Phyllis and Neff - Phyllis marked, in a sense as the possession of a man she despises, and Neff, who finds the anklet almost as fascinating as the woman who wears it. The anklet is a sexual bond between the two.
If you've never seen this impressive movie, by all means get hold of it (DVD, BluRay, streaming, rental, library - whatever meets your needs). I'm sure you'll be as enamored of it as we are. We'll close this with an early scene (and one which also raised a flag with the Breen office), Walter's first conversation with Phyllis (and you'll get to see the infamous anklet):