In Glacier Cave-In, Ranger Bill and his team are drawn to a newly discovered cave near Naughty Pine, which has the potential to unveil significant archaeological findings. The excitement is palpable as they learn about the cave's history, including evidence of ancient civilizations that could change the understanding of North America's past. However, the cave's location beneath a glacier raises immediate concerns about safety, as the glacier's movements could lead to catastrophic rockslides.