|Season 1, Episode 1|
|Air date||13 May 2013|
|Written by||Allan Cubitt|
|Directed by||Jakob Verbruggen|
Crime drama series set in Northern Ireland. When a murder in Belfast remains unsolved after 28 days, DSI Stella Gibson is called in to review the case. 
Detective Superintendent Stella Gibson arrives to Belfast from London to review a murder case that involves a young woman, daughter in law of Morgan Monroe, the chairman of the Northern Ireland Policing Executive. To welcome her there is her old partner Jim Burns that advises some political friction that investigations could lead to the department. Meanwhile, we see the daily routine of a young psychologist who juggles family - a wife and two children - and work. Apparently, he doesn't seem to have anything to do with the case, until he is shown breaking into a house and leaving on the bed female sexy underwear arranged so ambiguous. When the house’s owner, Sarah Kay, came back home, she called the police immediately, but Paul Spector has already disappeared so the cops – Ferrington and Stone - cannot do anything but reassure her, telling her to spend the night with a family member and to change the locks. In the following days, Paul continues stalking the woman following her to the park and a bar, where also known another girl alike. at his home, also receives ambiguous glances from teenager babysitter Katie.
During her investigation, Stella finds a link between the death of Alice Monroe and that of another woman killed three months before, that resembles particularly the victim of her case. Stella begins to believe that these are serial killings, but Jim Burns tells her not to suspect conspiracies everywhere and simply carry out her work. Not at all discouraged, Gibson asks her team to review all previous cases of break-ins into houses and stealing underwear. Danielle Ferrington, one of the policewomen who had been at the home of Sarah Kay, suspected that the young lawyer is in danger.
Later we see Paul at work with the Tyler's, a married couple who have recently lost a child and while the woman is alone with the psychologist, Paul secretly portrays her naked on his notepad. At the end of the consultation, Paul is attacked by James Tyler who didn't like Paul's questions, which he considers too invasive and threatens him violently. Meanwhile, Stella takes a look to the rest of the Monroe family and notes that the former husband of the victim, Aaron Monroe, is a cocaine addict.
While Ferrington is taking Gibson back to the hotel, they found the police barricades, which is investigating a shooting for drugs. Stella then makes the acquaintance of Sergeant James Olson, that she implicitly invites to go to bed with her. The following night, after having lied to his wife about having to go to his part-time job on the anti-suicide phone, Paul breaks into Sarah Kay's house and kills her, just as the two police officers who had been there the previous night on petrol to check that Sarah is at home, but being tied to the bed overwhelmed by the killer, the woman cannot answer.
- Gillian Anderson as DSI Stella Gibson
- Jamie Dornan as Paul Spector
- Niamh McGrady as PC Danielle Ferrington
- Bronagh Waugh as Sally Ann Spector
- Aisling Franciosi as Katie Benedetto
- John Lynch as ACC Jim Burns
- Archie Panjabi as Dr. Reed Smith
- Laura Donnelly as Sarah Kay
- Ben Peel as DS James Olson
- Frank McCusker as DCI Garrett Brink
- Ian McElhinney as Morgan Monroe
- Stuart Graham as DCI Matt Eastwood
- Emmett Scanlan as DC Glenn Martin
- Nick Lee as Ned Callan
- Sarah Beattie as Olivia Spector
- David Beattie as Liam Spector
- Séainín Brennan as Liz Tyler
- Brian Milligan as Jimmy Tyler
- Gerard Jordan as PC Brian Stone
- Gerard McCarthy as Kevin McSwain
- Eugene O'Hare as Aaron Monroe