In chapter one, Dill impresses Jem by telling him he had seen the movie Dracula. Up to that point, the only movies that Jem said he had seen in town were the Jesus movies shown in the courthouse, and he eagerly asks Dill to tell him all about the film. The narrator chooses not to include Dill's description. All she says is that "Dill reduced Dracula to dust," and that Jem thought it sounded much better than the book. It foreshadows the idea that reality can be scarier and, at times, a lot harder than fiction.
Their mutual love for the works of writers such Edgar Rice Burroughs, Oliver Optic, and Victor Appleton results in a friendship that will last all summer. When they get bored, their minds turn to the real-life character of Boo Radley.
As the narrator states:
Inside the house lived in a malevolent phantom. People said he existed, but Jem and I had never seen him. People said he went out at night when the moon was down and peeped on them. When people's azaleas froze in a cold snap, it was because he had breathed on them. Any stealthy small crimes committed in Maycomb were his work.
What should have been a description of Count Dracula has become the description of a real person. This is just, of course, the work of a child's overactive imagination, and later in the book the reader will see that Boo is in fact one of the good guys. The real monsters are the people that Scout least expects.