Claudia Hammond visits HMP Grendon, the only prison in Europe which operates wholly as a therapeutic community. More than nine out of ten prisoners at Grendon are serving indeterminate sentences for murder or serious violent offences. Inmates have to apply for a place and once approved undergo intensive group therapy three times a week for well over a year. Claudia talks to inmates, therapists and prison staff to find out how the prison operates and how its unique environment aims to reduce reoffending rates.