A botched operation leads Customs Officer 'Ash' to join a new undercover law enforcement team, that uses high-tech methods to catch high-level criminals. His knowledge of the street soon proves vital in tackling a major drug gang.

The Unit use phone taps to help track a large sum of money in the hope that it will lead them to the 'Mr Big'. But they also lead the team to a family that Ash is determined to protect - despite their illegal activities.