In the aftermath of the tragedy, Calder questions Patrick about Annie who, while he didn't particularly like Annie or her relationship with John, insists he had nothing to do with her murder. Thanks to Angus' exaggerated testimony of his attack, Tosh and Calder finally get a search warrant for the facility. There, they find a hidden basement where sinister, possibly illegal, activity has taken place.In an interview with Dr Mohan, she reveals the identity of the mastermind behind the operation. Tosh and Calder consider whether this person could have been responsible for the deaths of Annie and Bergen. However, before they can connect the lab to the double murder, they go in search of vulnerable teen Astrid Jakobson, who's suddenly gone missing. Believing her to be an important witness, Tosh and Calder are up against it, both worrying that Astrid's elaborate efforts to escape the Isles will put her in grave danger.At the Bett house, Ian is stunned to find Rossi in the garden talking to Noah. He leaves with an ominous promise – Rossi will put things right for Annie. Hearing of the encounter, Calder worries what Euan Rossi is really doing in Shetland.