Marlowe wakes up in the morning, disgusted by women. He gets dressed and walks outside to into a rain-filled day, only to realize that the gray Plymouth sedan that had been tailing him is parked across the street. He runs through his mind, wondering who might be in the car. When Marlowe gets to his office building, he confronts the man in the Plymouth, who has followed him the whole way, and tells him that if he has anything to say he can go upstairs and talk to Marlowe in his office. In characteristic style, he leaves the man behind and walks up to his office to find a check for $500 from General Sternwood. The buzzer rings and the little man from the Plymouth appears. His name is Harry Jones.
Harry Jones has information that he is willing to sell Marlowe for $200. Marlowe guesses that Agnes Lozelle is somehow involved in this offer. Jones's information is that Mona Grant did not run away with Regan, but that she is instead being kept in a hideout by Eddie Mars so that everyone will keep on believing Regan ran off with her.
Jones also brings Lash Canino, Mars's gunman, into the picture. Jones says that he came about this information through Joe Brody, who was investigating the Regan-Mona situation because he was trying to make money off of it. Amidst it all he saw Mrs. Regan in a car with Canino. Mrs. Regan knows Canino and Canino is Mars's friend. Therefore, Joe Brody came to the conclusion that Canino knows something about Regan and is trying to make his own money off of the situation.
Agnes stumbled upon Mona Grant by coincidence. Jones says that Agnes will tell Marlowe where Mona's hideout is when he gives Agnes the money. Marlowe does not quite understand why or how Harry and Agnes are doing this. Jones responds, "[Agnes is] a grifter, shamus. I'm a grifter. We're all grifters. So we sell each other out for a nickel." Jones tells Marlowe to bring the money to the office—Puss Walgreen's office, which fronts as an insurance company, and which we have already heard of through Brody. Once Jones has the money, he will take Marlowe to Agnes, who will hand over the information.
At 7:00 that evening, Marlowe makes his way to Puss Walgreen's office. As he approaches he hears talking coming from the office. Canino is inside. Marlowe enters quietly through the adjacent door and overhears the conversation. Canino wants to know why Jones's Plymouth has been following the detective around. Mars knows about it, he says, and Mars wants an explanation. Jones tells Canino he is trying to blackmail Marlowe for money for Agnes's drug habit, because Jones has information about Carmen Sternwood's whereabouts on the night of Brody's murder. Jones knows that Carmen had been at Geiger's and had also attempted to shoot Brody because of a photograph of her he had in his possession. Jones tires to convince Canino that the fact he is following Marlowe has nothing to do with Mars.
Canino asks Jones where Agnes is. Jones will not give up the information, so Canino points a gun at him. Finally, Jones gives Canino an address, and it initially seems Canino is going to let it go at that. However, before he leaves, Canino offers Jones a drink. The drink is poisoned with cyanide, and Jones drops to the floor, dead. Marlowe waits until Canino leaves, at which time he goes into the office and discovers Jones's dead body.