Escape from Memory by Margaret Peterson Haddix
When Kira allows her friends to hypnotize her at a sleepover party, Kira begins telling them strange things. Her friends tell her that it sounds like she really didn't come from California and that she was escaping a war. Kira tells her mom what happened and her mom acts frightened. she tells Kira never to let that happen again.
Then, one day, Kira comes home to find her mom gone. The lady at her work says she took a month off. A strange women calling herself "Aunt Memory" tells Kira that her mom has been kidnapped and takes her to a strange town. Can Kira trust this women? What do the people in the town want with her and her mother?