Katie Paterson's public artwork, Hollow, will be made out of 10,000 samples of different tree species and unveiled in Bristol in early May. This film follows Katie over a ten-month period as she assembles the wood collection and creates the artwork. Sourced from all around the world, her samples include the oldest tree in the world, a tree that survived a nuclear blast, and many trees that are now extinct. Katie's quest to collect tree samples takes her to an arboretum in Scotland and the national wood collection at Kew, to create an artwork designed to inspire wonder at the evolution of trees through time and the fragility of life on our planet.