Mountain ranges across the globe set the stage for this episode of the Hostile Planet wildlife series, tracking animals that survive at altitude where oxygen thins, temperatures swing violently, and footing can mean life or death. In Greenland's Jameson Land, inside the Arctic Circle, barnacle geese nest on sheer cliffs to keep their goslings out of reach of predators, then face the terrifying descent to the ground below. The film moves on to the Himalayas, following creatures built for thin air and near-vertical terrain, using close camera work on rock faces, snowfields, and exposed ridgelines to show exactly how each species clings to survival. Predators, weather, and food scarcity all play their part, and the camera stays with individual animals long enough to turn their daily gamble into a real story rather than a highlight reel. Bear Grylls narrates, framing each region as a test that only the best-adapted pass.