Avi writes:

This is the only book I’ve written with another writer. How did that happen? I have a twin sister (Emily Leider) who is also a writer. She writes biographies of real people. I once suggested she write my biography. Like a good sister, she said “I’ve got better things to do with my time.” I told that story to my writer friend Rachel Vail, and Rachel’s response was, “I’ll write one with you.”

We set up some rules: We would write alternate chapters. Each would be free to rewrite the other’s work. There would be no telling the other to hurry up. All of this we did, and it was great fun.

Note: there’s not a sentence in the book that we did not both write.