Previously published under title: The gold diggers club.

When Carly and her friends decide to do their history project on Brother XII, they think they've hit the jackpot. After all, the notorious cult leader was rumored to have buried a large stash of gold on the island where Carly's family has a cabin. But the girls' plans to get both the gold and great grades are complicated when the weather turns nasty and they find themselves stranded on the wrong side of the island. Will they find Brother XII's treasure?