The police investigate an apparent break-in that results in the death of Derek Irons, his wife and youngest daughter. Two older children survived the attack but one is in serious condition and in a coma. Irons was a ruthless businessman who targeted his rivals' customers resulting in regular confrontations. Irons was stabbed but his wife and daughter were shot. Sam is reunited with an old friend from Northern Ireland, Det. Supt. Tony Ashton who is the senior investigative officer on the case. Harry assists the police with the death of an old woman who is believed to have fallen down a staircase. His post-mortem reveals evidence that is not consistent with a fall.

The police continue their investigation into the deaths of several members of the Irons family but based on the forensic evidence, they now believe he may have been killed elsewhere and then transported to his home. When one of Irons' two surviving children is killed, they look to his circle of friends and family for a possible motive. Thanks to Harry's information, the police investigate further into the death of an elderly woman who supposedly fell down the stairs in her home. Supt. Tony Ashton clearly wants to renew his friendship with Sam but she isn't so sure. Leo's home life is in turmoil and it's been affecting his work.

Leo Dalton investigates the death of a young boy whose body is found in the river. He was badly abused and his hands and feet were severed. The child is found to have been HIV positive and the pathologists determine that he may have been the victim of a ritual killing., perhaps as part of an exorcism that went too far. When the skeletal remains of another child are found, Leo believes the police have focused their investigation on the wrong man. Nikki Alexander investigates the apparent suicide of Father Anthony Reid who appears to have jumped from his apartment window on the grounds of a well-known Catholic school. He had colon cancer but those who knew him question that he would take his own life. Harry Cunningham looks into the case of Austin Chambers who is found floating in his swimming pool with an obvious ligature mark on his throat.

When a second person, Vincent Fricks, is found dead with ligature marks around his neck, Nikki and Harry not only find a connection between the two dead men but also with the school where Father Reid committed suicide. They also find another common link between the three. Leo Dalton continues his investigation into a local church that combines Christian with African beliefs and customs. He manages to find physical evidence linking one of the dead boys to the church.

A post-mortem on a victim of domestic violence brings back troubling memories for Nikki.

With Jenny's murder unresolved, her friends at the women's refuge seek answers.