From the outside, Kirsten and Walker have nothing in common.  Kirsten is a rich, white girl who lives in a nice home with her parents and sister.  Walker is a black boy who lives with his single mom in a run-down part of town.  Choldenko writes an interesting story about two middle schoolers who start out as strangers, and end up supporting each other through the trials of family and life in 7th grade.  In the process, Kirsten and Walker discover that they have more in common than they ever could have imagined.