A new BBC 2 documentary tells the story of talented British climber Tom Ballard, who disappeared on Nanga Parbat in February 2019 aged 30. Tom was the son of the late and highly accomplished mountaineer Alison Hargreaves, who died while descending from the summit of K2 in 1995 aged 33. Director Chris Terrill weaves snapshots of Tom and his sister Kate Ballard's childhood spent in the mountains with footage of the last climbs of both Alison and Tom, and Kate's pilgrimages to visit their final resting places, 25 years apart.