Lincoln has been dominated by its castle for over 1000 years. Its high stone walls and gatehouses were built to impress the locals with Norman power, and it has housed medieval dungeons and Victorian and Georgian jails. Extraordinarily, today the castle is still a centre for justice and punishment, containing an active court. As part of a £19million refurbishment programme, a preparatory archaeological dig at the castle is revealing new secrets about the horrors of its early jails. Sir Tony Robinson and the Time Team cameras have had exclusive access to the dig. With help from Phil Harding and Alex Langlands, Tony traces the story of punishment over the course of a millennium. He discovers that, behind the walls of Lincoln Castle, the Victorians launched an experiment in prison justice that pushed human beings to their limits. Some went mad, many died, and the prison regime broke down in shocking circumstances. In this grim jail in the heart of the city, something went badly wrong. This Time Team Special explores the hidden corners of this spectacular site and the extensive historical records to find out why.