DI Perez investigates the disappearance of a vulnerable young man, whose family are new to Shetland. Has whatever they are running from come back to haunt them?

Mounting evidence pushes Perez and the team to revise their view of Connor Cairns. Is he a vulnerable missing person or a killer on the run?

Perez tries to get the measure of Lloyd. Evidence emerges of another bombmaker. The net closes in around Martin. Sandy uncovers Connor’s interest in a piece of local history.

Perez and his team face a race against time to prevent disaster striking Lerwick. With nowhere left to run, an increasingly desperate killer looks to make a devastating political. As the investigation draws to a close, Perez faces a life-changing decision.

A Met detective returns to Shetland on the trail of a vulnerable witness. DI Ruth Calder must team up with Tosh to find the girl before it’s too late.

Calder and Tosh must work together to find the armed killers and prevent further disaster. Howell and Nowak take refuge with a local and wait for a means of escape.

Unnerved by her discovery, Calder decides to stay on in Shetland. Tosh welcomes the support, as the revelation of a tattoo sends the case in a sinister new direction.

Tosh believes she has the murderer in custody and tasks the team with finding the evidence to charge. Calder suffers in silence with Jean’s revelation.

When her friend doesn’t get home one night, Tosh persuades DI Calder – now a resident of the Isles – that something is wrong.