Well the one of the most suspicious things in the book is when Jamie sees her own face on the milk carton, hence the title.
Hannah is likely the one who kidnapped Jamie, but with good intentions. Jamie's grandparents weren't at fault.
The clues revealed very little, just that Hannah's conflct with the cult hindered her ability to take care of Jamie.
Conflict was resolved when they found each other again.
Jamie found evidence to every aspect of the alleged kidnapping, including the dress in the picture, which she found in the attic.
Hope this helps!
