Stella Gibson has finally arrested Paul Spector, but he has been shot by jealous husband James Tyler, leaving the staff at Belfast General Hospital battling to save his life. As the shooting hits the news, the powers-that-be question Gibson's handling of the case, while Spector's young partner-in-crime Katie plots to help him.

Gibson and Burns are hauled over the coals by the Police Ombudsman and the Policing Executive for their conduct and handling of the case. When Spector’s name is released to the press as the arrested suspect in the Belfast Strangler case, his wife and family are forced to deal with the consequences.

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.

Gibson continues her hunt for the killer.

When a murder in Belfast remains unsolved after 28 days, DSI Stella Gibson is called in to review the case.

DSI Stella Gibson's worst fears are realised as Spector's murder spree in Belfast continues and she faces very real consequences after a reckless decision.

As DSI Stella Gibson takes control of the hunt for the serial killer striking women in Belfast, the realisation that his perfect kill is tainted pushes Spector into looking for his next victim.

After the breakthrough identifying the killer, Stella Gibson must play a waiting game.

As the investigation tightens around Paul Spector, he makes a bold break for cover.

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.

Stella Gibson realises that her mistakes have put the life of Rose Stagg in danger.

A shocking revelation proves how terrifyingly manipulative Paul Spector can be.

When Eastwood's investigation into Olson's murder throws open some uncomfortable truths for Burns, Gibson comes under increased pressure in her hunt for Belfast's killer.

The killer's latest attack gives Gibson renewed impetus. As the net appears to be closing in, Spector makes a dramatic confession and a decision that binds his fate to Gibson.

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.

With Paul Spector in custody, DSI Gibson searches for clues to help find Rose Stagg.