The main character Miranda lives in inner city New York in the 1970's; she and her mother dwell in a tenement apartment. There is a group of boys who hang around her neighborhood, and one day one of them punches Miranda's friend Sal in the stomach. After this incident, Sal does not come around Miranda's home. Later, since she has lost her friend, she is forced to seek friendship elsewhere. Because of this circumstance, she meets Marcus, with whom she becomes friends as they are both interested in time travel. This meeting with him changes Miranda's life forever.
In Chapter 8, one day Miranda explains to Marcus how she survives in her neighborhood:
I have my own trick. If I'm afraid of someone on the street, I'll turn to him (it's always a boy) and say, "Excuse me, do you happen to know what time it is?" This is my way of saying to the person "I see you as a friend, and there is no need to hurt me or take my stuff. Also, I don't even have a watch and I am probably not worth mugging."
This idea is also part of the theme of Time. The time travel that Marcus and Miranda speak of often is essential to the climactic scene in which Marcus wishes to apologize to Sal for having struck him, but Sal flees, only to be nearly struck by a car until the "laughing man" (who is the older Marcus) saves him. In fact, the neighborhood setting is crucial because it allows the "laughing man" to be outside the apartments whereas in another neighborhood, he would probably be made to leave.