Detective inspector Frank Paterson joins the team to reopen a thirty year old bullion robbery after he has tracked down the getaway car. Two guards died, allegedly at the hands of vicious Michael Denby - the fourth man in the robbery, who, unlike the other three, was never accounted for and is still at large. Frank and Sandra do not get on and she is sceptical when he claims that John Felsham, now a deputy assistant commissioner, was a bent copper who tipped Denby off, Felsham telling her that Frank has long held a personal grudge against him. However Felsham arrives unexpectedly at a back street pub once used by Denby where Frank and Gerry are following a lead and Frank fights him. As a result Felsham wants UCOS disbanded. But the team are determined to carry on and, backed by Strickland, they make sure that they get their man.