Incidental Influences

You don't really know it was an example of foreshadowing until the novel comes full circle, and you read the ending. Bob Ewell swears revenge on Atticus and decides to take it out on his children, Jem and Scout. He attacks them in the dark after Scout's play, and the end result is Jem's broken arm from trying to fight off Bob. Boo kills Bob thus saving the children and carries Jem home to his father.