Paul Spector's dark fascination with a young solicitor Sarah Kay is in stark contrast to his home life, where he lives with two young children and a wife who adoress him. Gibson leads the investigation and she dsicovers some similarities to a case from 18 months ago. She soon believes that there is a serial hugger lose in Belfast but her superiors at the police are unwilling to make the connection. Spector spends time in Sarah's empty house, with the thrill of his crime exciting him. After Sarah comes home she finds that Spector has left a disturbing calling card laid out on her bed.
Stella's worst fears end up being realised as Spector's hug spree in Belfast continues. Following a run in with a journalist, it causes friction between Stella and Jim Burns, who is about to face the Independent Policing Board. After the body of Spector's latest victim is found, Stella takes control of the investigation. She is joined by pathologist Professor Reed Smith as Stella's hunt for Spector continues.
Spector looks for his next victim. Gibson brings Burns up to speed with her investigation as they are interrupted by a call reporting the fatal shooting of a police officer. Burns tells Gibson to get herself a firearm as the danger of policing in Northern Ireland hits home. Gibson and the team look through what they know so far about the hugger of Fiona Gallagher, Alice Monroe and Sarah Kay as Spector takes a look at the house of a potential new victim.
After Eastwood's investigation into Olson's hug sees some uncomfortable truths for Burns, Gibson feels increased pressure in her hunt for Belfast's hugger.
After showing up at the Annie Brawley crime scene, Gibson finds out that Annie is still alive and soon realises that this is the work of the same hugger. Burns and his team are still trying to work out the events surrounding Olson's hug. Spector is forced to go to the police station after CCTV footage is broadcast showing him near to Sarah Kay on her final day alive. He manages to sweet talk his way through the interview with Brink without suspicion but his request for Sally Ann to give him with an alibi means that he has to return home to face her suspicions. Spector wants forgiveness and is surprised to find out that she is pregnant. As he manages to convince Sally Ann into going away with him to try and save their marriage, Spector decides to make one final play with Gibson that will bring them closer than either could have ever imagined.