Uncharted is book by Catherine Hapka in the "Gates Family Mystery Series" published in August 26, 2008 by Disney Press.
The Revolutionary War has been won. The United States of America is now struggling to redraw her boundaries. And as new territories are claimed and named, two siblings discover the high price of freedom.
Adam Benjamin Gates and his twin sister, Eleanor, have heard their father's tales of his part in the Revolutionary War and his discovery of a great treasure that helped the Patriots win. But they long for an adventure of their own. So when they hear whispers of a voyage to explore the recently purchased Louisiana Territory, the sibling are determined to take part. Soon, Adam and Eleanor find themselves on a dangerous journey into uncharted lands. But the greatest danger is yet to come when they uncover a treasure map hidden deep in the wilderness.