How about finding a letter in her library book which says:
This is hard. Harder than I expected, even with your help. But I have been practicing, and my preparations go well. I am coming to save your friends life, and my own.
I ask two favors.
First, you must write me a letter.
Second, please remember to mention the location of your house key.
The trip is a difficult one. I will not be myself when I reach you.
What does this all mean? Read When You Reach Me by Rebecca Stead if you want to find out the answer. Its a dandy book. The chapter headings are questions from the $20,000 Pyramid. The characters are great. The action is absorbing. I didnt want to put it down. Despite what I thought as I was reading it, it all comes together in the end, although you need to think about it. Im still thinking about it. Im not actually sure I get it, so maybe if you read it and understand it, you can explain it to me. However, it doesnt lessen my enjoyment of the book. Time will travel fast when you read When You Reach Me.