A double missing person's case blurs the lines between the personal and the professional, as Calder and Tosh are drawn into a labyrinthine investigation. When Tosh's friend, Annie Bett, goes missing she suspects something is seriously wrong. Ruth Calder - now living in Shetland - has no time to recover from a life-threatening ordeal of her own, as together they set out in search of Annie and her young son, Noah.

The acclaimed murder-mystery series is back for a thrilling, new six-part tale, as Met detective Ruth Calder returns to the Shetland Isles on the trail of a vulnerable witness, teaming up with Tosh on a case that will test their fragile, new partnership.