Henry, Jessie, Violet, and Benny Alden are going to climb a mountain! The hike up Old Flat Top is only supposed to take a day, but a dangerous rockslide changes everything. The rockslide reveals a hidden cave that just may hold a legendary treasure. Can the Boxcar Children solve the mystery of what's on top of the mountain? Graphic Planet is an imprint of Magic Wagon, a division of ABDO Group. Grades 2-4.