Mientras Brian enfrenta acciones disciplinarias por una muerte bajo custodia de su pasado, el resto del equipo descubre el arma que mató al narcotraficante Christian Highsmith en 1998. La misma arma mató a un niño joven, Danny Bossano, en 1982 en Gibraltar, un puerto de escala para los barcos en los que supuestamente Christian escondía las drogas. El equipo de UCOS va a Gibraltar para reunirse con el superintendente Cruz, el jefe local de casos sin resolver, quien cree que Danny era parte de la banda de contrabando de drogas. El hecho de que el arma fuera de uso militar también lleva al evasivo comandante Adam Sinclair, mientras Sandra interroga al dueño del casino Harry Truman, quien había sido amigo de Christian. Gerry y Steve visitan el casino de Truman pero accidentalmente quedan encerrados en un contenedor de envío mientras que el agente de envío Gordon Fletcher, asociado de Truman, es encontrado muerto.

UCOS reopen the thirty year old murder of porn king Jim Hockney when his daughter Sara reveals that a DNA test proves she is not his daughter. Her mother Jane cannot provide any answers as she and Jim both had several sex partners. Jim's girlfriend at the time, singer Angela Gold, was charged but acquitted of the murder and now seems to have disappeared. Brian's replacement Dan Griffin arrives, albeit late and is initially treated with hostility by Gerry, who thinks he is a spy. Nonetheless Dan tracks down Angela though in the meantime Sandra learns that Jim's brother Colin sold Jim's porn empire very shortly after his death to his main rival Gavin Reason. Furthermore Jane and Gavin were lovers, Gavin proving to be Sara's father though he was unaware at the time. However it is Gerry's collection of some of Jim's old films, supposedly confiscated by Vice Squad, that identifies the murder weapon and leads to the culprit. The case closed the team watch Angela perform at Ronnie Scott's Jazz Club.