Found by Margaret Peterson Haddix

Found : Paperback : SIMON & SCHUSTER : 9781416954217 : 141695421X : 21 Apr 2009 : One night a plane appears out of nowhere, the only passengers aboard: 36 babies. As soon as they are taken off the plane, they vanish. Now, 13 years later, two of those children are receiving sinister messages, and they begin to investigate their past.