The story begins in medias res with a postcard. Mom, who is a single mother and a paralegal, is preparing for an appearance on the game show $20,000 Pyramid. Miranda, her sixth-grade daughter and latchkey kid, is considering writing a letter to some unnamed "you" who has been sending her letters. This "you" also told her about the game show postcard before it even arrived. Who is this "you" and how is he/she able to predict the future? It's a mystery to us – and to Miranda.
Miranda and her mom live in New York City and the year is 1979. Mom has a boyfriend named Richard who is a lawyer and who has one leg that is a little bit shorter than the other – he visits often and helps Mom prepare for her game show appearance. As for Miranda, her favorite book is A Wrinkle in Time, and she carries a copy around with her constantly. (This book will play a pretty big part in the novel, just so you know. If you haven't read A Wrinkle in Time already, you can read about it on Shmoop.) There's also a homeless man called "the laughing man," who appears to be a little bit crazy and who lives outside of Miranda's apartment and sleeps with his head under the mailbox. (Hint: He's important.)
Moving on… If Miranda were going to write a letter, she tells us, it would all start the day that Sal got punched. Sal is her former best friend who won't walk home from school with her anymore. Miranda narrates the story of the day their friendship ended – the day Sal got randomly punched in the face by a boy in a green army coat. Sal wouldn't talk to Miranda after that and started playing a lot of basketball.
From this point on in the book we move between two timelines: Miranda and her mom in the present (right before her mom goes on $20,000 Dollar Pyramid) and Miranda's story of what happened after Sal got punched in the face last fall.
To continue the story of last fall, lots of things start happening after Sal gets punched and he and Miranda stop hanging out. First, Miranda meets the kid in the green army coat on the street. He's kind of weird, can read time without a watch, and is super into math and physics. Miranda's not afraid of him, though. They become something kind of like friends. The two have a conversation in the school's dentist office about A Wrinkle in Time and time travel.