The series concludes as Gibson and Anderson put fresh evidence to Spector, with explosive results. Spector's new-found friendship with another inmate develops, with devastating consequences.
Spector's legal team are determined that he will never stand trial. Anderson and Ferrington make a discovery from the past that may help Gibson build her case.
Gibson comes face to face with the depths of Sally-Ann's desperation.
Spector's legal team move into action, determined he won't stand trial.
When the Police Service of Northern Ireland are unable to close a case after 28 days, Detective Superintendent Stella Gibson of the Metropolitan Police Service is called in to review the case. Under her new leadership, the local detectives must track down and stop a serial killer who is terrorising the city of Belfast.