Stuart Evans is 40 years old and in the advanced stages of AIDS. When he dies the night after his birthday party no one thinks anything of it but his parents donate his remains to scientific study. When Sam and Trevor start an examination of the remains, they notice needle marks and suspect his death may not have been straightforward. Their suspicions are confirmed when the toxicology reports indicate an extremely high level of morphine. Mark Tate is also an AIDS sufferer who has been told that he will soon go blind. He too dies suddenly and when the police learn that he and Evans had the same physician, they begin to suspect doctor-assisted suicide.

As Sam continues her forensic investigation into the two deaths, the police make an arrest but soon realize they have the wrong person in custody when a crucial piece of evidence is uncovered. Sam discovers the true identity of the person behind the deaths but rather than tell the police, she decides to let him to turn himself in. Unfortunately, this leads to a tragic result. In her personal life, Sam and Peter Ross renew their long-ago romance.

Whilst cage-fighting Jack takes on young Dean Fallon, drug dealer and son of career criminal Terry Fallon. When policeman Sam Honeywell's corpse is discovered in his burnt out car Dean is the main suspect after Honeywell had arrested him but is released for lack of evidence. Sam's colleague Carl Parry is then arrested when it is made known that Carl's wife Kate was having an affair with the dead man. After Dean has fallen out with his friend Jason Simons over Dean's girlfriend Tess Hughes Tess finds drugs hidden in her father Stan's garage, which she takes to Jason. Soon afterwards he too is killed.

Following Simons' death he is revealed to have been an undercover policeman infiltrating the Fallons' drug dealing empire. Tess questions her father and is shocked to learn that he is part of the gang before Stan gets a visit from Fallon's lawyer telling him to say nothing. There will be another death and a shoot-out before the killer is finally exposed.