The compelling story of 30-year-old climber Tom Ballard, who disappeared on one of the Himalaya's most deadly mountains in February 2019. Tom was the son of mountaineer Alison Hargreaves, who perished on K2 in 1995. Mother and son, two of the greatest climbers of all time, died at almost the same age in the same mountain range, both doing what they loved best. They now lie forever encased in the ice of the high Himalayas. Left behind to cope with the enduring tragedy are Tom's sister, Kate, and their father, Jim. In 1995, Jim Ballard took his children, six-year-old Tom and four-year-old Kate, on an expedition to K2's basecamp to say farewell to their mother. The result was a BBC film, Alison's Last Mountain. Now, The Last Mountain follows Kate Ballard on a parallel trip to say goodbye to her brother on Nanga Parbat. Using archive from 1995 and Tom's own extraordinary footage taken up until the days before his death, the film explores what made Tom continue his ascent with Italian climber Daniele Nardi after the other two members of the expedition turned back. The film features revealing interviews with those left behind. Combining 25 years of intimate, unseen family archive with footage of the family that director Chris Terrill has shot in the years since, the documentary tells the unforgettable story of a family who lived - and were prepared to die for - the love of scaling the icy heights of the world's highest peaks. It explores what it is that drives people to pit themselves against nature at its most ferocious and unforgiving.