Exposition (Initial Situation)
Miss Wonderly Hires Herself a PI
Miss Wonderly's middle name is trouble. Well, not literally. But when she walks into the office of detective Sam Spade, he knows she's trouble, with a capital T. Miss Wonderly needs Spade's help to protect her from Thursby, who appears to have information on the whereabouts of Miss Wonderly's sister. Spade, along with his partner Miles Archer, agree to do what they can, partly because it's their job to help people out, and partly because who could say no to such a knockout.
Rising Action (Conflict, Complication)
Miss Wonderly Isn't Miss Wonderly
Miss Wonderly in fact has no sister and her real name is Brigid O'Shaughnessy (we warned you she was trouble). Brigid had been hired by Gutman to recover the long lost relic known as the Maltese Falcon. But her partner Cairo double-crossed her and she was left empty-handed. Brigid lures Spade into helping her track down the falcon, and the action continues to escalate as Spade gets closer and closer to finding the black bird.
Climax (Crisis, Turning Point)
Technically, there are several climaxes in this novel since the action is constantly rising and falling as Spade moves from one clue to the next in his search for the falcon. But the climax of all climaxes takes place when a mysterious man staggers into Spade's office. He dies (from six gunshot wounds to the chest) right before handing a bulky package to Spade. Inside the package is the jewel-encrusted Maltese falcon. All the cards are now in Spade's favor because he's in possession of the one object that everyone has been fighting over.
Gutman offers to pay Spade ten grand in exchange for the falcon, and Spade agrees on the condition that they find a fall guy to take the blame for the murders of Archer and Thursby. Gutman reluctantly agrees to hand over Wilmer (who of course feels betrayed, who wouldn't?).
When Spade produces the falcon, Gutman can't wait to get his greedy fat hands on it. But when Gutman scratches the surface of the falcon to make sure it's real, he finds that the inside is made out of black coal. It's a fake. With the falcon turning out to be worthless, the bad guys have nothing left for them in San Francisco, and are forced to flee.
Love or the Law?
Brigid suggests to Spade that they should run away together, but Spade has other plans. He confronts Brigid about Archer's death and accuses her of murdering him. She denies it at first, but finally confesses that she was trying to pin the murder on Thursby. Spade admits that he has feelings for her, but that he can't let her get away with killing his partner.
In the end, Spade sacrifices his love for Brigid by turning her in, but it's hard to be certain whether he does this to avenge his partner's death or to keep his own neck out of trouble.