Facing a dead end in the hunt for Galbraith's killer, Tosh leads Perez to the remote island of Fetlar. Donna asks Duncan for one last favour.
When a prominent and controversial Shetlander is murdered, Perez returns from his mother's funeral to lead an investigation that stretches across the Isles and out to sea.
In the aftermath of the diving incident, the team searches for a link between the two bodies. Meanwhile, Perez must deal with the return of Donna Killick.
The hunt is on for Sandy's attacker. Perez struggles to balance the case with his father's deteriorating condition, before a shocking confession throws the investigation down a new path and sows the seeds of further violence.
After the shocking events of the previous night, Perez must piece together what happened before a rampaging and vengeful Creggan finds his target.
Facing a dead end in the hunt for Galbraith's killer, Tosh leads Perez to the remote island of Fetlar. Donna asks Duncan for one last favour.
As Perez closes in on the identity of Galbraith's killer, he struggles with Duncan's secret, while Donna has one more surprise in store. (Final)
