After a mysterious disappearance on the canal, Jock turns up in Belfast gun-running for the IRA during the 'troubles'. He hatches a more lucrative scheme with a Palestinian and the story follows the conspiracy to divert weapons to the Black September Organisation. Helen, Jock's erstwhile partner in a previous black market scam, is reunited with her son after a prison sentence and she fears for her safety while Jock is at large. We follow the arms shipment by road, Grand Union Canal and sea to a destination on the Suffolk coast where Jock is ultimately served his final retribution.