The Maltese Falcon takes place in San Francisco, and starts out in the office of private detectives Spade and Archer. A Miss Wonderly arrives, announced by loyal secretary Effie Perrine. She wants to engage their agency to find her sister, whom she says has run off with a man named Floyd Thursby. Wonderly tells Sam Spade and Miles Archer that she has arranged a meeting with Thursby for that night at 8 pm. She gives them $200 in advance, wanting them to tail Thursby and warns them that he is a violent criminal. Miss Wonderly leaves and Miles goes out soon afterwards to tail Thursby.
Later in the morning, Sam goes to the office and finds Iva Archer waiting for him. She asks him if he killed Miles, then cries and apologizes. Sam kisses her, and it becomes obvious that he has been having an affair with Miles' wife. After getting Iva out of the office as quickly as possible, Sam tells Effie to get rid of all of Archer's stuff. Effie tells him that when she went to tell Iva about Miles' death, Iva pretended to have been asleep, but that she had actually been out and returned only a few minutes before Effie got there. Sam goes to Miss Wonderly's hotel to talk to her, but she has checked out. Returning to his office, he is informed by Effie that Wonderly called; she's now at a different hotel under an assumed name: Miss Leblanc.
Later that day, back at the office again, Spade is called upon by a rather effeminate man named Joe Cairo. He offers Sam $5000 for a figurine of a black bird which he seems to assume Spade has, or knows where to get. When Spade is not forthcoming, Cairo pulls a gun on him and says that he is going to search the office for the bird. He attempts to check Spade for a concealed weapon, but this ends badly when Sam seizes the opportunity to overpower Cairo and knock him out. Spade then searches Cairo's pockets, finding among other things, a ticket to the Geary theater for that night, a newspaper clipping about the two murders, and Sam's address written on a piece of note paper from the Hotel Belvedere. When Cairo wakes up, Spade questions him, but he refuses to say who he's working for. He does, however, renew his offer of $5000 for the bird. For that price, Sam agrees to look into the matter.