The Living Brain tells the inspiring story of William and Jean and their involvement in a unique study of the ageing brain led by Professor Ian Deary. As in life, the brain has many branches and connections; both William and Jean sat the Scottish Mental Survey at the age of 11, William in 1932 and Jean in 1946. After the original results of these studies were rediscovered in the 1990s, the Lothian Birth Cohorts were established. These studies look at ways in which the cognitive ability of the brain changes as we grow older, and this film reflects on the lives of those who take part in them.