For their second outing at Nature Trackers Adventure Camp, Buddy, Tiny, Shiny, Don and other friends learn about the tree line as they set out to hike up a mountain. Shiny is determined to get to the top of mountain forest. Buddy wonders if they’ll be able to see anything from the mountaintop, through the tall trees. The kids are amazed that the higher they hike, the shorter trees and bushes get! Then they reach the tree line — a certain point on the mountain, where trees are really small because they don’t have enough air to breathe and the temperature is too cold. In the end, Shiny and all the kids use teamwork to all reach the mountaintop together!