Like Sam Spade, in the book the reader is left to wonder what is the big secret his client is keeping. The movie loses a lot of suspense by letting the viewer into it immediately. I don’t think Bogart was (physically) able to convey the Mephistophelian looks Hammett intended for Spade, but he did a very good job. Bogart made a more charming, not a so slimy sort of hard-boiled dick. Mary Astor most definitely conveyed the character’s psychological traits, not her beauty and youth—Miss Astor was then 35 years old, ten years too old for Hammet’s Brigid. I loved Peter Lorre as the effeminate Joel Cairo; but unfortunately Gladys George couldn’t get in the skin of the sexy Iva Archer of the book. Although a film noir, it didn’t carry to the screen the heaviness the book pages exuded. All in all, it was a very good movie, that I enjoyed more than the book--and kept quite close to the book's plot.