Following the brutal attack on crofter , DI Jimmy Perez (Douglas Henshall) is forced to reassess the direction of his investigation. Perez suspects Jo was targeted because she witnessed Sally McColl speaking to a key person of interest shortly before Sally's death.

In the penultimate episode of gripping fourth season, the investigation into the 23-year-old murder of Lizzie Kilmuir and the recent death of Sally McColl reaches a fever pitch. As DI Jimmy Perez struggles to maintain control of the case, new arrivals and escalating tensions on the islands threaten to derail his search for the truth. Plot Summary: A Community on Edge

The term in your search is likely a remnant from older internet file-sharing terminology.

By the final shot—Perez staring out at the North Sea, Malone’s file in his hand, unclosed—you realize the real crime isn’t the murder. It’s the system that made the murder feel inevitable.