Grenada’s revolutionary leader was executed in a coup in 1983, with seven others. The whereabouts of their remains are unknown. Now, The Washington Post’s Martine Powers uncovers new answers about how the U.S. fits into this 40-year-old Caribbean mystery.

Lillian journeys above the Arctic Circle to one of the most remote and least visited National Parks. In our series finale, she confronts the question facing its future: whether a portion of this untouched wilderness will soon include a path for industry.

Lillian climbs the dunes for a view of a park imprinted with ancient human history and the beginnings of the Atomic Age. In doing so, she tries to understand why America’s deserts have been both safeguarded and sacrificed.

Lillian slogs through the marsh and steps back in time to explore how past mistakes devastated the “River of Grass.” What will it take to restore this unique landscape of water and sky? Along the way, the park’s wildlife has a thing or two to say.

Lillian experiences the rush of Glacier’s Going-to-the-Sun Road, but her most illuminating stops happen on the Blackfeet reservation. As Native people push for a greater hand in managing national park lands, Lillian asks whether that could ever happen.

Lillian begins her journey in the place that helped inspire the national parks. As wildfires threaten Yosemite’s giant sequoias, she asks what it will take to correct past mistakes and ensure the survival of these ancient trees.

Journey through the messy past and uncertain future of America’s national parks. The Washington Post’s Lillian Cunningham ventures off the marked trail to better understand the most urgent stories playing out in five iconic landscapes today.