Matt Baker, Sean Fletcher and Margherita Taylor are in the Cairngorms, where Matt meets Tilly Smith and her herd of 150 reindeer. The reindeer roam wild and free and a team of scientists are studying their grazing habits to assess its impact on the environment. Sean spends the day with ten-year-old Xander Johnson, who is part of a big effort to save one of the UK's rarest insects - the pine hoverfly, found only in two places in the Cairngorms and under threat in both of them. Margherita learns all about mountain safety and why smartphones should not be trusted out in the wild. She also hears from Amanda Thomson, an academic who is on a mission to preserve disappearing Scots words and whose work has inspired Marina Dennis, a crofter keen to preserve old crofting traditions and the language used to describe them.