Plot: DC Terry Perkins is undercover in prison, where he investigates convicted paedophile Charles Mawdsley who is believed to be running a paedophile ring with the help of one of the prison guards. DS Ramani de Costa appears as a prison counsellor, acting as Terry's contact with the outside world, but when Terry opens up in a group therapy session, Ramani begins to suspect that he was abused as a child