Door four: clue to the past

Lanie Gendis anything but ordinary. She goes to a school that teaches Indian stuff rather than math and English. Her mother, aunt, and uncle are crazy about Indian stuff. And she is completely alone.
Well, until Terissa shows up. She has just as a messed up life as Lanie does. The only difference is that she has a dad instead of a aunt and uncle.
Since Terissa showed up, Lanie's life flips upside down. Her mother finally explains everything, which causes the family to vacation. Somehow, though, Teerissa's family went on the exact vacation. What are they doing there? Could they be against them? Or are they with them? Find out in "Door Four: Clue to the Past".