Marcella links a teen's disappearance to Reg Reynolds and recovers a shocking memory from her last blackout; a vengeful Dawkins targets Marcella's son.

Marcella learns the horrifying truth about the scale of the killer's crimes when she discovers the murderer's lair.

The arrest of Vince Whitman causes massive fallout between Tim and Marcella. Meanwhile, Postfeed24's internet viral video leads the team to discover another body much closer to home.

Having discovered a key fact about the killer, Marcella returns to Nigel Stafford's home to uncover the truth behind his false allegations about Vince, but the truth leads to tragedy for the team.

Eric's arrest leads Marcella to Gail's workplace, where she makes a dreadful discovery about Joel; under hypnosis, Marcella remembers Juliet's death.

Marcella is working deep undercover as Keira, investigating the Maguires, a crime family in Belfast.

Rav heads to Belfast to investigate Bobby, while Marcella delves deeper into the Maguires' criminal world.

Rav discovers Marcella is working undercover. Elsewhere, tough-guy Jack is released from prison and rejoins the Maguire family.

Marcella's mental state is beginning to fracture, while Bobby is arrested and Katherine takes control of the city by getting rid of those in her way.

Marcella investigates the truth about Bobby, while Stacey attempts to escape the family with her baby.

The origins of the Keira persona are revealed and and Marcella realises the extent to which her past is still haunting her.