Hammett doesn't devote any space to explaining the characters' feelings and motivations through internal or narrative monologues. The reader has to figure everything out from their dialogue alone. In the book, Sam Spade is described as looking like a blonde Satan in contrast to the tall, dark, and handsome Humphrey Bogart. The film portrays Spade as being a bit clearer in his moral code compared to the book, but not by much. Book Spade is more hard hearted and aggressive. Film noir paints a picture of the world that is grim and cynical, almost nihilistic. The cops are incompetent jerks. Women are often hysterical and always untrustworthy. The crooks are venal thugs; seldom will you find the Moriarty style criminal mastermind. Spade himself is no virtuous white knight: he had an affair with his partner's wife who wanted to divorce her husband for Spade, though Spade remains noncommittal and dismissive.
The book and film are 70-80 years old so spoilers won't be behind a cut. The book opens with Miss Wonderly coming to Spade and his partner Miles Archer asking for help. She wants them to tail a Floyd Thursby. Archer is shot dead on the job. Miss Wonderly, who is actually Brigid O'Shaughnessy, pulled the trigger. She had hoped that Thursby would notice he was being tailed and try to take out Archer. If Thursby died, great. If Archer died, she'd hoped Thursby would be picked up for the killing. Thursby didn't take the bait and so she had to do it herself.
By the time Spade confronts O'Shaughnessy, we know that she manipulates men through sex, greed, and murder to accomplish her plans. She's slept with Spade by this point in the novel, and she expects that she can manipulate him like she has the others. Spade says that he won't play the sap for her. He didn't like his late partner, but when a detective's partner is murdered in cold blood something's gotta be done regardless of his personal feelings. O'Shaughnessy asks if Spade is really going to turn her over to the police after all they've shared together. Spade says that he'll wait the 20 years for her to get out of San Quentin, and if they execute her, he'll always have fond memories of her.
There's one scene in the book that's never been put on film. Spade tells O'Shaughnessy a story about a man he was hired to track down after he disappeared, leaving his wife and children behind. Spade eventually finds the man living in a different city, under an assumed name, working a new job, and married to another woman with children. Apparently the man had had a near fatal accident, and decided that life was too fleeting to always be doing the same thing day in and day out. But he doesn't really change. He's got a new life so to speak but it's almost identical to the one he left behind. Why does Spade tell this story? Hammett doesn't spell it out for us.
One of the morals of the story is that a man's gotta stick to his moral code, whatever it may be, regardless of the corruption and filth that may surround him, regardless of his personal feelings. Does Spade love O'Shaughnessy? It doesn't matter. She killed his partner, a partner he particularly like, and she has to answer for it. Throughout the story, Spade expertly plays each side against the other in order to reach the truth. He divides the antagonists by telling them he won't give them the Falcon unless they agree on someone to be the fall guy and go down for the murders of Thursby, Archer, and a Captain Jacobi. Wilmer Cook is the fall guy. Kasper Gutman delivers one of the coldest lines in all of fiction: "You were like a son to me. But if one loses a son, one can always have another. There is only one Maltese Falcon." Damn. Even to a guy like me that's pretty harsh. Not surprisingly, Cook shoots Gutman at the end of the story as the cops are hot on their trail.
5/5, would read again.