A severed hand washes up on a Shetland beach, with further body parts discovered in a holdall that has been dumped at sea. Perez and the team begin a complex murder investigation.

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.

Hoping to find information on Paul Kieran, Jimmy goes to Glasgow. There, he and DI Sam Boyd from the trafficking unit pursue some leads. Plus, Jimmy can't visit Glasgow without seeing Cassie, which brings her to the attention of the people tailing Jimmy and puts her in danger, too.

Having heard of the traumatic events in Glasgow, an angry Duncan confronts Jimmy over his fears for Cassie's safety. Cassie, although shaken, seems pleased that Jimmy has trusted her with the truth. Grant, young plain clothes officer, is tasked with keeping an eye on her. Now sure that Zezi is still being held on Shetland, Jimmy and Sandy pay a visit to Morag Dunwoody...

The discovery of Nikki's body intensifies the search for Zezi. Perez feels that time is running out. A desperate Olivia tries to get information from Jamie Hayes.

Perez closes in on Zezi's location at last. But can he reach her before it's too late?