Found by Margaret Peterson Haddix
This book is great!
How many 13 year olds get letters in the mail that state "You are one of the missing!" Another letter comes and states "they are coming to get you!" In addtion to this suspense this 13 year old feels that he needs to hide this information from everyone because he is adopted and he doesn't know where to turn. He doesn't want to hurt his family (or are they his family)? When he finally tells a friend, he states that he has gotten these letters too! But how can he get the same letters and who are they from?
If you like mysteries and stories of friendship this is a must read!