The team is called in after Mr. Stickley of the Police complaints Board feels that something is not right about an armed police raid on a house where several people were killed, including one of the officers and a mystery woman. A young Muslim called Melik has been badly wounded and lies in hospital. Mr. Stickley believes the policeman was killed by Rhys Allen, a colleague who was having an affair with the deceased's wife. Melik's sister Isra confides in Nikki that all the 'suspects' were unarmed and not terrorists and fears of a cover-up by the authorities are not helped by the aggressive attitude of Inspector Transfield, particularly when Nikki is attacked and evidence stolen from her laptop.

Harry Dalton and DI Helen Okoroafor manage to identify the dead woman from the scene of the raid - who turns out to be a DS who was working undercover and who the police refused to identify when the pathologists submitted her DNA sample to them. While DI Tranfield continues to search for the terrorist cell that he is sure is about to strike, Nikki Alexander continues to try and piece the evidence together from the scene of the raid but clearly there are pieces missing. A re-creation of the shooting shows her what happened and also identifies the only person in the right position to have shot the police officer.

Following the discovery of a young woman's corpse in a forest Nikki and Jack travel to Scotland to assist DS Jason Ross, who mistrusts local pathologist Dr Jenkins. Prime suspect is hunter and gunsmith Niall Wallace but he is eliminated from enquiries. A clue leads to the Manhattan strip club, owned by Stella Nelson, who identifies the dead girl as Caitlin, who apparently gave no surname. Another dancer Amy tells Jack that Caitlin disappeared after getting into a car with a stranger but the local police, obnoxious DS MacNeil and DI Laing were not interested when she reported Caitlin missing. Five more female corpses are discovered in the forest, denoting a serial killer. When news of the murders becomes public Sarah O'Keefe tells her boyfriend Steve Boyd that some years earlier she escaped a rapist and would-be killer in the same forest but, as she goes to tell the police, she is abducted again.

Nikki and Jack , joined by the apparently decent Dr Jenkins, unearth more bodies, leading to Niall being rearrested. Steve Boyd reports girlfriend Sarah missing, revealing to Jack what she had told him about her previous ordeal, whilst Jason Ross admits to Nikki he called her in because he felt that in the past Jenkins had colluded with Mac Neil and Laing to falsify evidence. In fact Jenkins confesses to Nikki that he had been forced to lie because Laing spent most of his time covering for loose cannon MacNeil and needed his help. The pathologists return to the Manhattan and learn that almost all the victims had worked there, including, very briefly, Sarah. As a result Stella makes a phone call to Laing regarding her son Jerome. Laing finally confesses to Nikki, Jack and DS Ross about his relationship with Stella, which consequently leads to them finding Sarah and identifying the serial killer.