Last episode in the series about a fella called Ash, who is "a talented customs agent with a troubled past". (They always have troubled pasts, don't they?) He was head-hunted to join UNIT - an elite team of law enforcers that operates beyond the jurisdiction of the police - their mission is to track down hardcore criminals. Tonight's finale sees Roach's identity finally revealed, and with the villain seemingly within the Unit's grasp, the team now faces the challenge of intercepting his massive shipment of drugs and ensuring there's evidence to link it to him. But how far is Ash prepared to go to bring down his nemesis?