[1] The series follows DS Annie Redford (Laura Fraser), a small town police officer with the Scottish Highland Police as she investigates the murder of piano teacher Niall Swift, who is found dead at the bottom of a cliff in the picturesque village of Lochnafoy, Loch Fyne, Inveraray.
When it becomes apparent that part of Swift's brain has been removed, and a human heart belonging to another victim is found close by, Annie's team realise they are searching for a serial killer.
In response, Glasgow based major investigation detective DCI Lauren Quigley (Siobhan Finneran) is brought in to lead the enquiry.
[2] Supporting cast includes Don Gilet as psychological profiler Blake Albrighton, John Sessions as Annie's boss DCI Frank Smilie, Gray O'Brien as Alan Redford, Annie's husband, and William Ash as local tourist operator Leighton Thomas.
Internationally, broadcast under the title Loch Ness, the series premiered in Australia on 20 April 2017 on BBC First[6] and in the United States on 19 June 2017 on subscription streaming service Acorn TV.