Perez finds that the murder of the young Nigerian man is more than just the drugs trade but could be sex trafficking with the Shetlands a cog in a much larger wheel.
The episode starts with discovery of members of the Hayes family found slaughtered, a rather dodgy family makes him think the crime is linked. The alternative is there are two sets of murderers running around the island.
Olivia (Rakie Ayola) the mother of the dead Nigerian man is on the frame for the murders of the Hayes. She was near their property the night they were killed. Of course Olivia also wants to save her daughter being held captive and she thinks now her son's death will not be important now some locals have ended up dead.
A Glasgow thug called Kiernan is suspected to be behind the trafficking. Fisherman Calum Dunwoody is bought in for questioning but he refuses to talk, he hints that the operation is huge with people everywhere. DC Sandy Wilson then makes an elementary mistake with him.
There is dry humour from Perez despite the grim circumstances. He also sympathises with Olivia's predicament and knows she could not had been involved in the deaths of the Hayes.
There are some bloody scenes in this episode, despite the high murder count it is still simmering than being on full burn mode. DC Wilson's actions amounts to gross stupidity.