In the 1980s archaeologist Harry Bell came to believe that Glasgow - a city built and re-built on over centuries - was laid out to a hidden design. For years he investigated the lost corners and invisible history of the landscape, plotting his 'Secret Geometry'. Unknown to Harry, psychiatric patient Mary Ross also wandered the city, visiting many of the same significant places. Her medical case file reveals a poignant quest to understand her troubled past and present. The Devil's Plantation unites the lives of these two strangers, retracing their steps to reveal an ancient secret and a timeless story of how we all live.