In the 1930s, borstal was a much-feared institution designed to reform young offenders by enforcing compulsory work, education, discipline and intense physical activity. In its heyday, the system worked, with low levels of reoffending, in stark contrast to today's statistics. In a social experiment, 13 trouble-makers - some of whom have criminal convictions - volunteer to become borstal boys, spending four weeks in a castle in Northumberland. Will the experience set them on the straight and narrow? Taking on the role of governor is one of the UK's leading criminologists, David Wilson.