Jimmy questions Donna about the shocking DNA results, Alison arrives in Norway in search of Andreas Hagan, and an unexpected twist leads Perez and Tosh into the murky world of…

Ignoring Secret Service warnings, Perez and Tosh track down Mathias Soderland. Back on Shetland, a beach memorial service is held for Sally McColl.

Perez must re-assess the investigation in the aftermath of the attack. The MIT arrives on Shetland and sets its sights on Malone. Meanwhile, Tosh begins to have doubts about Lars.