Calder and Tosh travel to the remote village of Lunniswick to investigate the brutal murder of an elderly woman. She has been out in the elements for several days.

In the aftermath of the fire, Tosh and Calder struggle to get answers from an unreliable suspect. A historic grudge from Eadie’s time as a social worker comes to light.

Events in Lunniswick turn violent as holidaymakers Chris and Hayley risk it all to clear their debts. A paranoid Stevie wants Amy all to herself.

While Calder pressures Louden for help and Tosh investigates Robert Tulloch, Stevie’s battle to keep her sister turns desperate.

As Calder and Tosh close in on the motive for Eadie’s murder, the pool of suspects narrows.