As Peter Latimer lies critically ill in hospital, Perez and Tosh examine the remains of the burnt out building. When they discover evidence that Peter was drinking that night, they wonder why he would leave the safety of his room at the Centre to drink alone, outside? When Latimer then dies from his injuries, Perez urges Sandy to find answers as to why Anna and Peter visited Lerwick two weeks before they both died. As Sandy re-examines the CCTV footage of the two victims, Perez questions Finlay Caulfield about the photographs of Anna on his camera. It is clear that Finlay was obsessed with Anna, but there is still not enough evidence to charge him with murder. Frustrated by so many unanswered questions, Perez decides to use the fact Finlay 'stalked' Anna and asks him directly if Anna was having an affair with Latimer. Finlay confirms she was - and that Frank knew about it. Sandy then reveals that the CCTV footage shows that Latimer was carrying a bag when he left Commercial Street in Lerwick - but not when he entered it. Perez believes the contents of this bag are the reason why Latimer disappeared on the morning of the murder. Its eventual discovery leads them to reveal a plot to blackmail Anna, but not a reason to murder her. It's not until Sandy comes up with a final piece of evidence - proof that one of the residents has been lying about his past - that finally leads Perez to the heart breaking truth.