Johnson, Aaron, 1976- National park mystery series #2

"Before leaving on a two-month summer vacation, Jake Evans finds a gift from his deceased grandfather that will lead him on a scavenger hunt through ten of America's most rugged, wild, and beautiful national parks."--Page 4 of cover

After camping in Rocky Mountain National Park, Jake and his friends travel to the Great Sand Dunes in southern Colorado. Exploring the heart of the dunes, they stumble upon something both unexpected and dangerous. Through more twists and turns, Jake's friendships and integrity are tested by choices that will demand smarts and courage. --Publisher description