An older man listens to Bill's story about being a callow writer who likes to follow strangers around around London, observing them. One day, a glib and self-confident man whom Bill has been following confronts him. He's Cobb, a burglar who takes Bill under his wing and shows him how to break and enter. They burgle a woman's flat; Bill gets intrigued with her (photographs are everywhere in her flat). He follows her and chats her up at a bar owned by her ex-boyfriend, a nasty piece of work who killed someone in her living room with a hammer. Soon Bill is volunteering to do her a favor, which involves a break-in. What does the older man know that Bill doesn't?