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.

As the investigation draws to a close, Tosh and Calder try to unravel the mystery at the heart of the Bains. The identity of the killer lies in the reason why Ellen left Shetland.