At the Sternwood mansion, Marlow asks for Mrs. Reagan but she's not in. Norris takes Carmen upstairs and offers to call a cab for Marlowe. But Marlowe refuses, to make sure there's no record that he's been there. Smart move.
Instead, Marlowe walks in the rain back to Geiger's house. Before reentering the house, he takes a swig of whiskey from the bottle he carries with him. He immediately notices that something's wrong. Two strips of silk are missing from the wall. And… wait for it… Geiger's body is gone.
Marlowe searches the house again, and uses Geiger's keys to open a locked bedroom. The room is different from the rest of the house—more "masculine," in Marlowe's words. He finds nothing there, so he locks the door again.
Marlowe comes to the conclusion that whoever moved the body wanted to make it look like Geiger is missing, not dead. Marlowe also believes that it wasn't the murderer who had hidden the body because the killer would've left quickly, fearing a witness may have seen him.
Marlowe decides that it's fine with him to keep the body hidden because it buys him more time. When he sits down to try and break the code in the notebook, all he can come up with is that it's a list of customers. There are at least four hundred entries in the list.