Down Terrace opens with Bill (Bob Hill) and his son Karl (Robin Hill) leaving a courthouse after a stint in jail. As soon as they get out, the pair try to figure out who ratted them out to the police. Its not exactly clear why Bill and Karl were locked up, but their habitual drug intake and shady dealings indicate that they are up to no good. Karl's wife (Julia Deakin) seems nice enough, but she is intricately involved in the skullduggery that got her husband and son locked up. Various suspicious characters enter the scenario, including hated family friend Garvey (Tony Way), a hit man named Pringle (Michael Smiley) who carries his toddler to jobs, Karl's pregnant girlfriend (Kerry Peacock), and a brutal oaf named Eric (David Schaal). Everyone suspects each other of being a snitch, and the paranoia blossoms into a deadly web of plots and schemes.