Marlowe drives to Geiger's bookshop to observe and see what kind of "business" goes on there. An attractive woman in a black dress, who walks "with a certain something [not] often seen in bookstores," greets Marlowe. He asks her several questions about a couple of first editions—which he has just researched at the public library—in order to test the woman's knowledge of rare books. The woman claims that the shop does not have what Marlowe is looking for.
Marlowe says he will wait for Geiger to come into the store, under the guise that perhaps Geiger may know a little more about the books Marlowe claims to be seeking. Marlowe sits down, waits, and observes, smoking a cigarette. He sees a man entering and leaving the back room with a wrapped package shaped like a book, but doing so with an air of mystery and suspicion. When the man with the parcel is about to leave, Marlowe gets up and proceeds to follow him. The man tries to lose Marlowe, but instead decides to play it safe and get rid of the incriminating package he is carrying. Marlowe picks up the wrapped book that the man has abandoned by tree. Thunder is still sounding outside.
Marlowe continues to collect clues. He goes to a phone booth to find Geiger's home phone number. He calls, but no one answers. It also dawns upon Marlowe to look for other bookstores in the area of Geiger's store. He finds a small place nearby and shows his detective badge to the woman at the front desk. Marlowe asks her the same questions he asked the girl at Geiger's shop—this woman, however, knows the answers and responds to one of his trick questions in a way that only someone who ran a real bookstore could. Marlowe tells the woman that the girl at Geiger's store could not answer the questions and did not pick up on his trick. Marlowe uses this evidence, along with his guile, to get a full description of Geiger from the woman.
On his way out of the bookstore Marlowe opens the package he has been carrying with him. He finds exactly what he knew he would: "smut." The nature of Geiger's racket is clear: he runs a lending library of pornography from the back room of his store, fronting the operation as a rare bookstore.
Marlowe continues to watch Geiger's store until a man meeting the description of Geiger enters. When Geiger leaves, Marlowe follows the man's car all the way to his house. As Marlowe watches the house, he sees a white car pull up and park in the driveway. A young woman gets out and enters Geiger's house. After she has gone inside, Marlowe checks the white car's registration and finds that it belongs to Carmen Sternwood.
A while later, having observed the house through the night, Marlowe sees a flash go off inside the house. He then hears a scream—one of shock more so than fear. As Marlowe approaches the house to see what is happening, he hears three gunshots and then footsteps coming from the house—the footsteps of someone escaping. Marlowe finally makes his way into the house through the window and sees that there are two people inside: "Neither of the two people in the room paid any attention to the way I came in, although only one of them was dead."